From 3182b4d9ec72e60efb261072ef91b6319fc50f90 Mon Sep 17 00:00:00 2001 From: Hynek Schlawack Date: Tue, 6 Mar 2018 15:57:41 +0100 Subject: [PATCH 01/15] Fix error_handling examples to use the ? operator --- README.md | 6 +++--- error_handling/errors2.rs | 6 +++--- error_handling/errors3.rs | 25 ++++++++++--------------- error_handling/errorsn.rs | 10 +++++----- 4 files changed, 21 insertions(+), 26 deletions(-) diff --git a/README.md b/README.md index c6d9d97..e673184 100644 --- a/README.md +++ b/README.md @@ -138,9 +138,9 @@ relevant. - ["option1.rs"](https://play.rust-lang.org/?code=%2F%2F+option1.rs%0A%2F%2F+This+example+panics+because+the+second+time+it+calls+%60pop%60%2C+the+%60vec%60%0A%2F%2F+is+empty%2C+so+%60pop%60+returns+%60None%60%2C+and+%60unwrap%60+panics+if+it%27s+called%0A%2F%2F+on+%60None%60.+Handle+this+in+a+more+graceful+way+than+calling+%60unwrap%60%21%0A%2F%2F+Scroll+down+for+hints+%3A%29%0A%0Afn+main%28%29+%7B%0A++++let+mut+list+%3D+vec%21%5B3%5D%3B%0A%0A++++let+last+%3D+list.pop%28%29.unwrap%28%29%3B%0A++++println%21%28%22The+last+item+in+the+list+is+%7B%3A%3F%7D%22%2C+last%29%3B%0A%0A++++let+second_to_last+%3D+list.pop%28%29.unwrap%28%29%3B%0A++++println%21%28%22The+second-to-last+item+in+the+list+is+%7B%3A%3F%7D%22%2C+second_to_last%29%3B%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+Try+using+a+%60match%60+statement+where+the+arms+are+%60Some%28thing%29%60+and+%60None%60.%0A%2F%2F+Or+set+a+default+value+to+print+out+if+you+get+%60None%60+by+using+the%0A%2F%2F+function+%60unwrap_or%60.%0A%2F%2F+Or+use+an+%60if+let%60+statement+on+the+result+of+%60pop%28%29%60+to+both+destructure%0A%2F%2F+a+%60Some%60+value+and+only+print+out+something+if+we+have+a+value%21%0A) - ["result1.rs"](https://play.rust-lang.org/?code=%2F%2F+result1.rs%0A%2F%2F+Make+this+test+pass%21+Scroll+down+for+hints+%3A%29%0A%0A%23%5Bderive%28PartialEq%2CDebug%29%5D%0Astruct+PositiveNonzeroInteger%28u64%29%3B%0A%0A%23%5Bderive%28PartialEq%2CDebug%29%5D%0Aenum+CreationError+%7B%0A++++Negative%2C%0A++++Zero%2C%0A%7D%0A%0Aimpl+PositiveNonzeroInteger+%7B%0A++++fn+new%28value%3A+i64%29+-%3E+Result%3CPositiveNonzeroInteger%2C+CreationError%3E+%7B%0A++++++++Ok%28PositiveNonzeroInteger%28value+as+u64%29%29%0A++++%7D%0A%7D%0A%0A%23%5Btest%5D%0Afn+test_creation%28%29+%7B%0A++++assert%21%28PositiveNonzeroInteger%3A%3Anew%2810%29.is_ok%28%29%29%3B%0A++++assert_eq%21%28Err%28CreationError%3A%3ANegative%29%2C+PositiveNonzeroInteger%3A%3Anew%28-10%29%29%3B%0A++++assert_eq%21%28Err%28CreationError%3A%3AZero%29%2C+PositiveNonzeroInteger%3A%3Anew%280%29%29%3B%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+%60PositiveNonzeroInteger%3A%3Anew%60+is+always+creating+a+new+instance+and+returning+an+%60Ok%60+result.%0A%2F%2F+It+should+be+doing+some+checking%2C+returning+an+%60Err%60+result+if+those+checks+fail%2C+and+only%0A%2F%2F+returning+an+%60Ok%60+result+if+those+checks+determine+that+everything+is...+okay+%3A%29%0A) - ["errors1.rs"](https://play.rust-lang.org/?code=%2F%2F+errors1.rs%0A%2F%2F+This+function+refuses+to+generate+text+to+be+printed+on+a+nametag+if%0A%2F%2F+you+pass+it+an+empty+string.+It%27d+be+nicer+if+it+explained+what+the+problem%0A%2F%2F+was%2C+instead+of+just+sometimes+returning+%60None%60.+The+2nd+test+currently%0A%2F%2F+does+not+compile+or+pass%2C+but+it+illustrates+the+behavior+we+would+like%0A%2F%2F+this+function+to+have.%0A%2F%2F+Scroll+down+for+hints%21%21%21%0A%0Apub+fn+generate_nametag_text%28name%3A+String%29+-%3E+Option%3CString%3E+%7B%0A++++if+name.len%28%29+%3E+0+%7B%0A++++++++Some%28format%21%28%22Hi%21+My+name+is+%7B%7D%22%2C+name%29%29%0A++++%7D+else+%7B%0A++++++++%2F%2F+Empty+names+aren%27t+allowed.%0A++++++++None%0A++++%7D%0A%7D%0A%0A%23%5Bcfg%28test%29%5D%0Amod+tests+%7B%0A++++use+super%3A%3A*%3B%0A%0A++++%2F%2F+This+test+passes+initially+if+you+comment+out+the+2nd+test.%0A++++%2F%2F+You%27ll+need+to+update+what+this+test+expects+when+you+change%0A++++%2F%2F+the+function+under+test%21%0A++++%23%5Btest%5D%0A++++fn+generates_nametag_text_for_a_nonempty_name%28%29+%7B%0A++++++++assert_eq%21%28%0A++++++++++++generate_nametag_text%28%22Beyonc%C3%A9%22.into%28%29%29%2C%0A++++++++++++Some%28%22Hi%21+My+name+is+Beyonc%C3%A9%22.into%28%29%29%0A++++++++%29%3B%0A++++%7D%0A%0A++++%23%5Btest%5D%0A++++fn+explains_why_generating_nametag_text_fails%28%29+%7B%0A++++++++assert_eq%21%28%0A++++++++++++generate_nametag_text%28%22%22.into%28%29%29%2C%0A++++++++++++Err%28%22%60name%60+was+empty%3B+it+must+be+nonempty.%22.into%28%29%29%0A++++++++%29%3B%0A++++%7D%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+%60Err%60+is+one+of+the+variants+of+%60Result%60%2C+so+what+the+2nd+test+is+saying%0A%2F%2F+is+that+%60generate_nametag_text%60+should+return+a+%60Result%60+instead+of+an%0A%2F%2F+%60Option%60.%0A%0A%2F%2F+To+make+this+change%2C+you%27ll+need+to%3A%0A%2F%2F+-+update+the+return+type+in+the+function+signature+to+be+a+Result+that%0A%2F%2F+++could+be+the+variants+%60Ok%28String%29%60+and+%60Err%28String%29%60%0A%2F%2F+-+change+the+body+of+the+function+to+return+%60Ok%28stuff%29%60+where+it+currently%0A%2F%2F+++returns+%60Some%28stuff%29%60%0A%2F%2F+-+change+the+body+of+the+function+to+return+%60Err%28error+message%29%60+where+it%0A%2F%2F+++currently+returns+%60None%60%0A%2F%2F+-+change+the+first+test+to+expect+%60Ok%28stuff%29%60+where+it+currently+expects%0A%2F%2F+++%60Some%28stuff%29%60.%0A) -- ["errors2.rs"](https://play.rust-lang.org/?code=%2F%2F+errors2.rs%0A%2F%2F+Say+we%27re+writing+a+game+where+you+can+buy+items+with+tokens.+All+items+cost%0A%2F%2F+5+tokens%2C+and+whenever+you+purchase+items+there+is+a+processing+fee+of+1%0A%2F%2F+token.+A+player+of+the+game+will+type+in+how+many+items+they+want+to+buy%2C%0A%2F%2F+and+the+%60total_cost%60+function+will+calculate+the+total+number+of+tokens.%0A%2F%2F+Since+the+player+typed+in+the+quantity%2C+though%2C+we+get+it+as+a+string--+and%0A%2F%2F+they+might+have+typed+anything%2C+not+just+numbers%21%0A%0A%2F%2F+Right+now%2C+this+function+isn%27t+handling+the+error+case+at+all+%28and+isn%27t%0A%2F%2F+handling+the+success+case+properly+either%29.+What+we+want+to+do+is%3A%0A%2F%2F+if+we+call+the+%60parse%60+function+on+a+string+that+is+not+a+number%2C+that%0A%2F%2F+function+will+return+a+%60ParseIntError%60%2C+and+in+that+case%2C+we+want+to%0A%2F%2F+immediately+return+that+error+from+our+function+and+not+try+to+multiply%0A%2F%2F+and+add.%0A%0A%2F%2F+There+are+at+least+two+ways+to+implement+this+that+are+both+correct--+but%0A%2F%2F+one+is+a+lot+shorter%21+Scroll+down+for+hints+to+both+ways.%0A%0Ause+std%3A%3Anum%3A%3AParseIntError%3B%0A%0Apub+fn+total_cost%28item_quantity%3A+%26str%29+-%3E+Result%3Ci32%2C+ParseIntError%3E+%7B%0A++++let+processing_fee+%3D+1%3B%0A++++let+cost_per_item+%3D+5%3B%0A++++let+qty+%3D+item_quantity.parse%3A%3A%3Ci32%3E%28%29%3B%0A%0A++++Ok%28qty+*+cost_per_item+%2B+processing_fee%29%0A%7D%0A%0A%23%5Bcfg%28test%29%5D%0Amod+tests+%7B%0A++++use+super%3A%3A*%3B%0A%0A++++%23%5Btest%5D%0A++++fn+item_quantity_is_a_valid_number%28%29+%7B%0A++++++++assert_eq%21%28%0A++++++++++++total_cost%28%2234%22%29%2C%0A++++++++++++Ok%28171%29%0A++++++++%29%3B%0A++++%7D%0A%0A++++%23%5Btest%5D%0A++++fn+item_quantity_is_an_invalid_number%28%29+%7B%0A++++++++assert_eq%21%28%0A++++++++++++total_cost%28%22beep+boop%22%29.unwrap_err%28%29.to_string%28%29%2C%0A++++++++++++%22invalid+digit+found+in+string%22%0A++++++++%29%3B%0A++++%7D%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+One+way+to+handle+this+is+using+a+%60match%60+statement+on%0A%2F%2F+%60item_quantity.parse%3A%3A%3Ci32%3E%28%29%60+where+the+cases+are+%60Ok%28something%29%60+and%0A%2F%2F+%60Err%28something%29%60.+This+pattern+is+very+common+in+Rust%2C+though%2C+so+there%27s%0A%2F%2F+a+%60try%21%60+macro+that+does+pretty+much+what+you+would+make+that+match+statement%0A%2F%2F+do+for+you%21+Take+a+look+at+this+section+of+the+Error+Handling+chapter%3A%0A%2F%2F+https%3A%2F%2Fdoc.rust-lang.org%2Fstable%2Fbook%2Ferror-handling.html%23the-try-macro%0A%2F%2F+and+give+it+a+%60try%21%60%0A) -- ["errors3.rs"](https://play.rust-lang.org/?code=%2F%2F+errors3.rs%0A%2F%2F+This+is+a+program+that+is+trying+to+use+a+completed+version+of+the%0A%2F%2F+%60total_cost%60+function+from+the+previous+exercise.+It%27s+not+working+though--%0A%2F%2F+we+can%27t+call+the+%60try%21%60+macro+in+the+%60main%28%29%60+function%21+Why+not%3F%0A%2F%2F+What+should+we+do+instead%3F+Scroll+for+hints%21%0A%0Ause+std%3A%3Anum%3A%3AParseIntError%3B%0A%0Afn+main%28%29+%7B%0A++++let+mut+tokens+%3D+100%3B%0A++++let+pretend_user_input+%3D+%228%22%3B%0A%0A++++let+cost+%3D+try%21%28total_cost%28pretend_user_input%29%29%3B%0A%0A++++if+cost+%3E+tokens+%7B%0A++++++++println%21%28%22You+can%27t+afford+that+many%21%22%29%3B%0A++++%7D+else+%7B%0A++++++++tokens+-%3D+cost%3B%0A++++++++println%21%28%22You+now+have+%7B%7D+tokens.%22%2C+tokens%29%3B%0A++++%7D%0A%7D%0A%0Apub+fn+total_cost%28item_quantity%3A+%26str%29+-%3E+Result%3Ci32%2C+ParseIntError%3E+%7B%0A++++let+processing_fee+%3D+1%3B%0A++++let+cost_per_item+%3D+5%3B%0A++++let+qty+%3D+try%21%28item_quantity.parse%3A%3A%3Ci32%3E%28%29%29%3B%0A%0A++++Ok%28qty+*+cost_per_item+%2B+processing_fee%29%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+Since+the+%60try%21%60+macro+returns+an+%60Err%60+early+if+the+thing+it%27s+trying+to%0A%2F%2F+do+fails%2C+you+can+only+use+the+%60try%21%60+macro+in+functions+that+have+a%0A%2F%2F+%60Result%60+as+their+return+type.%0A%0A%2F%2F+The+error+that+you+get+if+you+run+this+code+is%3A%0A%0A%2F%2F+%60%60%60%0A%2F%2F+error%3A+mismatched+types%3A%0A%2F%2F+expected+%60%28%29%60%2C%0A%2F%2F+found+%60std%3A%3Aresult%3A%3AResult%3C_%2C+_%3E%60%0A%2F%2F+%60%60%60%0A%0A%2F%2F+which+is+saying+that+the+expected+return+type+of+the+%60main%60+function+is%0A%2F%2F+the+empty+tuple%2C+but+we+tried+to+return+a+%60Result%60--+and+that%27s+happening%0A%2F%2F+in+the+implementation+of+%60try%21%60.+The+%60main%60+function+never+has+a+return+type%2C%0A%2F%2F+so+we+have+to+use+another+way+of+handling+a+%60Result%60+within+%60main%60.%0A%0A%2F%2F+Decide+what+we+should+do+if+%60pretend_user_input%60+has+a+string+value+that+does%0A%2F%2F+not+parse+to+an+integer%2C+and+implement+that+instead+of+calling+the+%60try%21%60%0A%2F%2F+macro.%0A) -- ["errorsn.rs"](https://play.rust-lang.org/?code=%2F%2F+errorsn.rs%0A%2F%2F+This+is+a+bigger+error+exercise+than+the+previous+ones%21%0A%2F%2F+You+can+do+it%21+%3A%29%0A%2F%2F%0A%2F%2F+Edit+the+%60read_and_validate%60+function+so+that+it+compiles+and%0A%2F%2F+passes+the+tests...+so+many+things+could+go+wrong%21%0A%2F%2F%0A%2F%2F+-+Reading+from+stdin+could+produce+an+io%3A%3AError%0A%2F%2F+-+Parsing+the+input+could+produce+a+num%3A%3AParseIntError%0A%2F%2F+-+Validating+the+input+could+produce+a+CreationError+%28defined+below%29%0A%2F%2F%0A%2F%2F+How+can+we+lump+these+errors+into+one+general+error%3F+That+is%2C+what%0A%2F%2F+type+goes+where+the+question+marks+are%2C+and+how+do+we+return%0A%2F%2F+that+type+from+the+body+of+read_and_validate%3F%0A%2F%2F%0A%2F%2F+Scroll+down+for+hints+%3A%29%0A%0Ause+std%3A%3Aerror%3B%0Ause+std%3A%3Afmt%3B%0Ause+std%3A%3Aio%3B%0A%0A%2F%2F+PositiveNonzeroInteger+is+a+struct+defined+below+the+tests.%0Afn+read_and_validate%28b%3A+%26mut+io%3A%3ABufRead%29+-%3E+Result%3CPositiveNonzeroInteger%2C+%3F%3F%3F%3E+%7B%0A++++let+mut+line+%3D+String%3A%3Anew%28%29%3B%0A++++b.read_line%28%26mut+line%29%3B%0A++++let+num%3A+i64+%3D+line.trim%28%29.parse%28%29%3B%0A++++let+answer+%3D+PositiveNonzeroInteger%3A%3Anew%28num%29%3B%0A++++answer%0A%7D%0A%0A%2F%2F+This+is+a+test+helper+function+that+turns+a+%26str+into+a+BufReader.%0Afn+test_with_str%28s%3A+%26str%29+-%3E+Result%3CPositiveNonzeroInteger%2C+Box%3Cerror%3A%3AError%3E%3E+%7B%0A++++let+mut+b+%3D+io%3A%3ABufReader%3A%3Anew%28s.as_bytes%28%29%29%3B%0A++++read_and_validate%28%26mut+b%29%0A%7D%0A%0A%23%5Btest%5D%0Afn+test_success%28%29+%7B%0A++++let+x+%3D+test_with_str%28%2242%5Cn%22%29%3B%0A++++assert_eq%21%28PositiveNonzeroInteger%2842%29%2C+x.unwrap%28%29%29%3B%0A%7D%0A%0A%23%5Btest%5D%0Afn+test_not_num%28%29+%7B%0A++++let+x+%3D+test_with_str%28%22eleven+billion%5Cn%22%29%3B%0A++++assert%21%28x.is_err%28%29%29%3B%0A%7D%0A%0A%23%5Btest%5D%0Afn+test_non_positive%28%29+%7B%0A++++let+x+%3D+test_with_str%28%22-40%5Cn%22%29%3B%0A++++assert%21%28x.is_err%28%29%29%3B%0A%7D%0A%0A%23%5Btest%5D%0Afn+test_ioerror%28%29+%7B%0A++++struct+Broken%3B%0A++++impl+io%3A%3ARead+for+Broken+%7B%0A++++++++fn+read%28%26mut+self%2C+_buf%3A+%26mut+%5Bu8%5D%29+-%3E+io%3A%3AResult%3Cusize%3E+%7B%0A++++++++++++Err%28io%3A%3AError%3A%3Anew%28io%3A%3AErrorKind%3A%3ABrokenPipe%2C+%22uh-oh%21%22%29%29%0A++++++++%7D%0A++++%7D%0A++++let+mut+b+%3D+io%3A%3ABufReader%3A%3Anew%28Broken%29%3B%0A++++assert%21%28read_and_validate%28%26mut+b%29.is_err%28%29%29%3B%0A++++assert_eq%21%28%22uh-oh%21%22%2C+read_and_validate%28%26mut+b%29.unwrap_err%28%29.to_string%28%29%29%3B%0A%7D%0A%0A%23%5Bderive%28PartialEq%2CDebug%29%5D%0Astruct+PositiveNonzeroInteger%28u64%29%3B%0A%0Aimpl+PositiveNonzeroInteger+%7B%0A++++fn+new%28value%3A+i64%29+-%3E+Result%3CPositiveNonzeroInteger%2C+CreationError%3E+%7B%0A++++++++if+value+%3D%3D+0+%7B%0A++++++++++++Err%28CreationError%3A%3AZero%29%0A++++++++%7D+else+if+value+%3C+0+%7B%0A++++++++++++Err%28CreationError%3A%3ANegative%29%0A++++++++%7D+else+%7B%0A++++++++++++Ok%28PositiveNonzeroInteger%28value+as+u64%29%29%0A++++++++%7D%0A++++%7D%0A%7D%0A%0A%23%5Btest%5D%0Afn+test_positive_nonzero_integer_creation%28%29+%7B%0A++++assert%21%28PositiveNonzeroInteger%3A%3Anew%2810%29.is_ok%28%29%29%3B%0A++++assert_eq%21%28Err%28CreationError%3A%3ANegative%29%2C+PositiveNonzeroInteger%3A%3Anew%28-10%29%29%3B%0A++++assert_eq%21%28Err%28CreationError%3A%3AZero%29%2C+PositiveNonzeroInteger%3A%3Anew%280%29%29%3B%0A%7D%0A%0A%23%5Bderive%28PartialEq%2CDebug%29%5D%0Aenum+CreationError+%7B%0A++++Negative%2C%0A++++Zero%2C%0A%7D%0A%0Aimpl+fmt%3A%3ADisplay+for+CreationError+%7B%0A++++fn+fmt%28%26self%2C+f%3A+%26mut+fmt%3A%3AFormatter%29+-%3E+fmt%3A%3AResult+%7B%0A++++++++f.write_str%28%28self+as+%26error%3A%3AError%29.description%28%29%29%0A++++%7D%0A%7D%0A%0Aimpl+error%3A%3AError+for+CreationError+%7B%0A++++fn+description%28%26self%29+-%3E+%26str+%7B%0A++++++++match+*self+%7B%0A++++++++++++CreationError%3A%3ANegative+%3D%3E+%22Negative%22%2C%0A++++++++++++CreationError%3A%3AZero+%3D%3E+%22Zero%22%2C%0A++++++++%7D%0A++++%7D%0A%7D%0A%0A%2F%2F+First+hint%3A+To+figure+out+what+type+should+go+where+the+%3F%3F%3F+is%2C+take+a+look%0A%2F%2F+at+the+test+helper+function+%60test_with_str%60%2C+since+it+returns+whatever%0A%2F%2F+%60read_and_validate%60+returns+and%60test_with_str%60+has+its+signature+fully%0A%2F%2F+specified.%0A%0A%2F%2F+Next+hint%3A+There+are+three+places+in+%60read_and_validate%60+that+we+call+a%0A%2F%2F+function+that+returns+a+%60Result%60+%28that+is%2C+the+functions+might+fail%29.%0A%2F%2F+Wrap+those+calls+in+a+%60try%21%60+macro+call+so+that+we+return+immediately+from%0A%2F%2F+%60read_and_validate%60+if+those+function+calls+fail.%0A%0A%2F%2F+Another+hint%3A+under+the+hood%2C+the+%60try%21%60+macro+calls+%60From%3A%3Afrom%60%0A%2F%2F+on+the+error+value+to+convert+it+to+a+boxed+trait+object%2C+a+Box%3Cerror%3A%3AError%3E%2C%0A%2F%2F+which+is+polymorphic--+that+means+that+l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+- ["errors2.rs"](https://play.rust-lang.org/?code=%2F%2F+errors2.rs%0A%2F%2F+Say+we%27re+writing+a+game+where+you+can+buy+items+with+tokens.+All+items+cost%0A%2F%2F+5+tokens%2C+and+whenever+you+purchase+items+there+is+a+processing+fee+of+1%0A%2F%2F+token.+A+player+of+the+game+will+type+in+how+many+items+they+want+to+buy%2C%0A%2F%2F+and+the+%60total_cost%60+function+will+calculate+the+total+number+of+tokens.%0A%2F%2F+Since+the+player+typed+in+the+quantity%2C+though%2C+we+get+it+as+a+string--+and%0A%2F%2F+they+might+have+typed+anything%2C+not+just+numbers%21%0A%0A%2F%2F+Right+now%2C+this+function+isn%27t+handling+the+error+case+at+all+%28and+isn%27t%0A%2F%2F+handling+the+success+case+properly+either%29.+What+we+want+to+do+is%3A%0A%2F%2F+if+we+call+the+%60parse%60+function+on+a+string+that+is+not+a+number%2C+that%0A%2F%2F+function+will+return+a+%60ParseIntError%60%2C+and+in+that+case%2C+we+want+to%0A%2F%2F+immediately+return+that+error+from+our+function+and+not+try+to+multiply%0A%2F%2F+and+add.%0A%0A%2F%2F+There+are+at+least+two+ways+to+implement+this+that+are+both+correct--+but%0A%2F%2F+one+is+a+lot+shorter%21+Scroll+down+for+hints+to+both+ways.%0A%0Ause+std%3A%3Anum%3A%3AParseIntError%3B%0A%0Apub+fn+total_cost%28item_quantity%3A+%26str%29+-%3E+Result%3Ci32%2C+ParseIntError%3E+%7B%0A++++let+processing_fee+%3D+1%3B%0A++++let+cost_per_item+%3D+5%3B%0A++++let+qty+%3D+item_quantity.parse%3A%3A%3Ci32%3E%28%29%3B%0A%0A++++Ok%28qty+*+cost_per_item+%2B+processing_fee%29%0A%7D%0A%0A%23%5Bcfg%28test%29%5D%0Amod+tests+%7B%0A++++use+super%3A%3A*%3B%0A%0A++++%23%5Btest%5D%0A++++fn+item_quantity_is_a_valid_number%28%29+%7B%0A++++++++assert_eq%21%28%0A++++++++++++total_cost%28%2234%22%29%2C%0A++++++++++++Ok%28171%29%0A++++++++%29%3B%0A++++%7D%0A%0A++++%23%5Btest%5D%0A++++fn+item_quantity_is_an_invalid_number%28%29+%7B%0A++++++++assert_eq%21%28%0A++++++++++++total_cost%28%22beep+boop%22%29.unwrap_err%28%29.to_string%28%29%2C%0A++++++++++++%22invalid+digit+found+in+string%22%0A++++++++%29%3B%0A++++%7D%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+One+way+to+handle+this+is+using+a+%60match%60+statement+on%0A%2F%2F+%60item_quantity.parse%3A%3A%3Ci32%3E%28%29%60+where+the+cases+are+%60Ok%28something%29%60+and%0A%2F%2F+%60Err%28something%29%60.+This+pattern+is+very+common+in+Rust%2C+though%2C+so+there%27s%0A%2F%2F+a+%60%3F%60+operator+that+does+pretty+much+what+you+would+make+that+match+statement%0A%2F%2F+do+for+you%21+Take+a+look+at+this+section+of+the+Error+Handling+chapter%3A%0A%2F%2F+https%3A%2F%2Fdoc.rust-lang.org%2Fbook%2Fsecond-edition%2Fch09-02-recoverable-errors-with-result.html%23a-shortcut-for-propagating-errors-%0A%2F%2F+and+give+it+a+try%21%0A) +- ["errors3.rs"](https://play.rust-lang.org/?code=%2F%2F+errors3.rs%0A%2F%2F+This+is+a+program+that+is+trying+to+use+a+completed+version+of+the%0A%2F%2F+%60total_cost%60+function+from+the+previous+exercise.+It%27s+not+working+though--%0A%2F%2F+we+can%27t+use+the+%60%3F%60+operator+in+the+%60main%28%29%60+function%21+Why+not%3F%0A%2F%2F+What+should+we+do+instead%3F+Scroll+for+hints%21%0A%0Ause+std%3A%3Anum%3A%3AParseIntError%3B%0A%0Afn+main%28%29+%7B%0A++++let+mut+tokens+%3D+100%3B%0A++++let+pretend_user_input+%3D+%228%22%3B%0A%0A++++let+cost+%3D+total_cost%28pretend_user_input%29%3F%3B%0A%0A++++if+cost+%3E+tokens+%7B%0A++++++++println%21%28%22You+can%27t+afford+that+many%21%22%29%3B%0A++++%7D+else+%7B%0A++++++++tokens+-%3D+cost%3B%0A++++++++println%21%28%22You+now+have+%7B%7D+tokens.%22%2C+tokens%29%3B%0A++++%7D%0A%7D%0A%0Apub+fn+total_cost%28item_quantity%3A+%26str%29+-%3E+Result%3Ci32%2C+ParseIntError%3E+%7B%0A++++let+processing_fee+%3D+1%3B%0A++++let+cost_per_item+%3D+5%3B%0A++++let+qty+%3D+item_quantity.parse%3A%3A%3Ci32%3E%28%29%3F%3B%0A%0A++++Ok%28qty+*+cost_per_item+%2B+processing_fee%29%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+Since+the+%60%3F%60+operator+returns+an+%60Err%60+early+if+the+thing+it%27s+trying+to%0A%2F%2F+do+fails%2C+you+can+only+use+the+%60%3F%60+operator+in+functions+that+have+a%0A%2F%2F+%60Result%60+as+their+return+type.%0A%0A%2F%2F+Hence+the+error+that+you+get+if+you+run+this+code+is%3A%0A%0A%2F%2F+%60%60%60%0A%2F%2F+error%5BE0277%5D%3A+the+%60%3F%60+operator+can+only+be+used+in+a+function+that+returns+%60Result%60+%28or+another+type+that+implements+%60std%3A%3Aops%3A%3ATry%60%29%0A%2F%2F+%60%60%60%0A%0A%2F%2F+So+we+have+to+use+another+way+of+handling+a+%60Result%60+within+%60main%60.%0A%0A%2F%2F+Decide+what+we+should+do+if+%60pretend_user_input%60+has+a+string+value+that+does%0A%2F%2F+not+parse+to+an+integer%2C+and+implement+that+instead+of+using+the+%60%3F%60%0A%2F%2F+operator.%0A) +- ["errorsn.rs"](https://play.rust-lang.org/?code=%2F%2F+errorsn.rs%0A%2F%2F+This+is+a+bigger+error+exercise+than+the+previous+ones%21%0A%2F%2F+You+can+do+it%21+%3A%29%0A%2F%2F%0A%2F%2F+Edit+the+%60read_and_validate%60+function+so+that+it+compiles+and%0A%2F%2F+passes+the+tests...+so+many+things+could+go+wrong%21%0A%2F%2F%0A%2F%2F+-+Reading+from+stdin+could+produce+an+io%3A%3AError%0A%2F%2F+-+Parsing+the+input+could+produce+a+num%3A%3AParseIntError%0A%2F%2F+-+Validating+the+input+could+produce+a+CreationError+%28defined+below%29%0A%2F%2F%0A%2F%2F+How+can+we+lump+these+errors+into+one+general+error%3F+That+is%2C+what%0A%2F%2F+type+goes+where+the+question+marks+are%2C+and+how+do+we+return%0A%2F%2F+that+type+from+the+body+of+read_and_validate%3F%0A%2F%2F%0A%2F%2F+Scroll+down+for+hints+%3A%29%0A%0Ause+std%3A%3Aerror%3B%0Ause+std%3A%3Afmt%3B%0Ause+std%3A%3Aio%3B%0A%0A%2F%2F+PositiveNonzeroInteger+is+a+struct+defined+below+the+tests.%0Afn+read_and_validate%28b%3A+%26mut+io%3A%3ABufRead%29+-%3E+Result%3CPositiveNonzeroInteger%2C+%3F%3F%3F%3E+%7B%0A++++let+mut+line+%3D+String%3A%3Anew%28%29%3B%0A++++b.read_line%28%26mut+line%29%3B%0A++++let+num%3A+i64+%3D+line.trim%28%29.parse%28%29%3B%0A++++let+answer+%3D+PositiveNonzeroInteger%3A%3Anew%28num%29%3B%0A++++answer%0A%7D%0A%0A%2F%2F+This+is+a+test+helper+function+that+turns+a+%26str+into+a+BufReader.%0Afn+test_with_str%28s%3A+%26str%29+-%3E+Result%3CPositiveNonzeroInteger%2C+Box%3Cerror%3A%3AError%3E%3E+%7B%0A++++let+mut+b+%3D+io%3A%3ABufReader%3A%3Anew%28s.as_bytes%28%29%29%3B%0A++++read_and_validate%28%26mut+b%29%0A%7D%0A%0A%23%5Btest%5D%0Afn+test_success%28%29+%7B%0A++++let+x+%3D+test_with_str%28%2242%5Cn%22%29%3B%0A++++assert_eq%21%28PositiveNonzeroInteger%2842%29%2C+x.unwrap%28%29%29%3B%0A%7D%0A%0A%23%5Btest%5D%0Afn+test_not_num%28%29+%7B%0A++++let+x+%3D+test_with_str%28%22eleven+billion%5Cn%22%29%3B%0A++++assert%21%28x.is_err%28%29%29%3B%0A%7D%0A%0A%23%5Btest%5D%0Afn+test_non_positive%28%29+%7B%0A++++let+x+%3D+test_with_str%28%22-40%5Cn%22%29%3B%0A++++assert%21%28x.is_err%28%29%29%3B%0A%7D%0A%0A%23%5Btest%5D%0Afn+test_ioerror%28%29+%7B%0A++++struct+Broken%3B%0A++++impl+io%3A%3ARead+for+Broken+%7B%0A++++++++fn+read%28%26mut+self%2C+_buf%3A+%26mut+%5Bu8%5D%29+-%3E+io%3A%3AResult%3Cusize%3E+%7B%0A++++++++++++Err%28io%3A%3AError%3A%3Anew%28io%3A%3AErrorKind%3A%3ABrokenPipe%2C+%22uh-oh%21%22%29%29%0A++++++++%7D%0A++++%7D%0A++++let+mut+b+%3D+io%3A%3ABufReader%3A%3Anew%28Broken%29%3B%0A++++assert%21%28read_and_validate%28%26mut+b%29.is_err%28%29%29%3B%0A++++assert_eq%21%28%22uh-oh%21%22%2C+read_and_validate%28%26mut+b%29.unwrap_err%28%29.to_string%28%29%29%3B%0A%7D%0A%0A%23%5Bderive%28PartialEq%2CDebug%29%5D%0Astruct+PositiveNonzeroInteger%28u64%29%3B%0A%0Aimpl+PositiveNonzeroInteger+%7B%0A++++fn+new%28value%3A+i64%29+-%3E+Result%3CPositiveNonzeroInteger%2C+CreationError%3E+%7B%0A++++++++if+value+%3D%3D+0+%7B%0A++++++++++++Err%28CreationError%3A%3AZero%29%0A++++++++%7D+else+if+value+%3C+0+%7B%0A++++++++++++Err%28CreationError%3A%3ANegative%29%0A++++++++%7D+else+%7B%0A++++++++++++Ok%28PositiveNonzeroInteger%28value+as+u64%29%29%0A++++++++%7D%0A++++%7D%0A%7D%0A%0A%23%5Btest%5D%0Afn+test_positive_nonzero_integer_creation%28%29+%7B%0A++++assert%21%28PositiveNonzeroInteger%3A%3Anew%2810%29.is_ok%28%29%29%3B%0A++++assert_eq%21%28Err%28CreationError%3A%3ANegative%29%2C+PositiveNonzeroInteger%3A%3Anew%28-10%29%29%3B%0A++++assert_eq%21%28Err%28CreationError%3A%3AZero%29%2C+PositiveNonzeroInteger%3A%3Anew%280%29%29%3B%0A%7D%0A%0A%23%5Bderive%28PartialEq%2CDebug%29%5D%0Aenum+CreationError+%7B%0A++++Negative%2C%0A++++Zero%2C%0A%7D%0A%0Aimpl+fmt%3A%3ADisplay+for+CreationError+%7B%0A++++fn+fmt%28%26self%2C+f%3A+%26mut+fmt%3A%3AFormatter%29+-%3E+fmt%3A%3AResult+%7B%0A++++++++f.write_str%28%28self+as+%26error%3A%3AError%29.description%28%29%29%0A++++%7D%0A%7D%0A%0Aimpl+error%3A%3AError+for+CreationError+%7B%0A++++fn+description%28%26self%29+-%3E+%26str+%7B%0A++++++++match+*self+%7B%0A++++++++++++CreationError%3A%3ANegative+%3D%3E+%22Negative%22%2C%0A++++++++++++CreationError%3A%3AZero+%3D%3E+%22Zero%22%2C%0A++++++++%7D%0A++++%7D%0A%7D%0A%0A%2F%2F+First+hint%3A+To+figure+out+what+type+should+go+where+the+%3F%3F%3F+is%2C+take+a+look%0A%2F%2F+at+the+test+helper+function+%60test_with_str%60%2C+since+it+returns+whatever%0A%2F%2F+%60read_and_validate%60+returns+and%60test_with_str%60+has+its+signature+fully%0A%2F%2F+specified.%0A%0A%2F%2F+Next+hint%3A+There+are+three+places+in+%60read_and_validate%60+that+we+call+a%0A%2F%2F+function+that+returns+a+%60Result%60+%28that+is%2C+the+functions+might+fail%29.%0A%2F%2F+Apply+the+%60%3F%60+operator+on+those+calls+so+that+we+return+immediately+from%0A%2F%2F+%60read_and_validate%60+if+those+function+calls+fail.%0A%0A%2F%2F+Another+hint%3A+under+the+hood%2C+the+%60%3F%60+operator+calls+%60From%3A%3Afrom%60%0A%2F%2F+on+the+error+value+to+convert+it+to+a+boxed+trait+object%2C+a+Box%3Cerror%3A%3AError%3E%2C%0A%2F%2F+which+is+polymorphic--+that+means+that+lots+of+different+kinds+of+errors%0A%2F%2F+can+be+returned+from+the+same+function+because+all+errors+act+the+same%0A%2F%2F+since+they+all+implement+the+%60error%3A%3AError%60+trait.%0A%2F%2F+Check+out+this+section+of+the+book%3A%0A%2F%2F+https%3A%2F%2Fdoc.rust-lang.org%2Fstable%2Fbook%2Fsecond-edition%2Fch09-02-recoverable-errors-with-result.html%23a-shortcut-for-propagating-errors-%0A%0A%2F%2F+Another+another+hint%3A+Note+that+because+the+%60%3F%60+operator+returns%0A%2F%2F+the+*unwrapped*+value+in+the+%60Ok%60+case%2C+if+we+want+to+return+a+%60Result%60+from%0A%2F%2F+%60read_and_validate%60+for+*its*+success+case%2C+we%27ll+have+to+rewrap+a+value%0A%2F%2F+that+we+got+from+the+return+value+of+a+%60%3F%60ed+call+in+an+%60Ok%60--+this+will%0A%2F%2F+look+like+%60Ok%28something%29%60.%0A%0A%2F%2F+Another+another+another+hint%3A+%60Result%60s+must+be+%22used%22%2C+that+is%2C+you%27ll%0A%2F%2F+get+a+warning+if+you+don%27t+handle+a+%60Result%60+that+you+get+in+your%0A%2F%2F+function.+Read+more+about+that+in+the+%60std%3A%3Aresult%60+module+docs%3A%0A%2F%2F+https%3A%2F%2Fdoc.rust-lang.org%2Fstd%2Fresult%2F%23results-must-be-used%0A) ### Standard library types diff --git a/error_handling/errors2.rs b/error_handling/errors2.rs index 05824c1..306eeba 100644 --- a/error_handling/errors2.rs +++ b/error_handling/errors2.rs @@ -66,7 +66,7 @@ mod tests { // One way to handle this is using a `match` statement on // `item_quantity.parse::()` where the cases are `Ok(something)` and // `Err(something)`. This pattern is very common in Rust, though, so there's -// a `try!` macro that does pretty much what you would make that match statement +// a `?` operator that does pretty much what you would make that match statement // do for you! Take a look at this section of the Error Handling chapter: -// https://doc.rust-lang.org/stable/book/error-handling.html#the-try-macro -// and give it a `try!` +// https://doc.rust-lang.org/book/second-edition/ch09-02-recoverable-errors-with-result.html#a-shortcut-for-propagating-errors- +// and give it a try! diff --git a/error_handling/errors3.rs b/error_handling/errors3.rs index 9b285e0..9c29af5 100644 --- a/error_handling/errors3.rs +++ b/error_handling/errors3.rs @@ -1,7 +1,7 @@ // errors3.rs // This is a program that is trying to use a completed version of the // `total_cost` function from the previous exercise. It's not working though-- -// we can't call the `try!` macro in the `main()` function! Why not? +// we can't use the `?` operator in the `main()` function! Why not? // What should we do instead? Scroll for hints! use std::num::ParseIntError; @@ -10,7 +10,7 @@ fn main() { let mut tokens = 100; let pretend_user_input = "8"; - let cost = try!(total_cost(pretend_user_input)); + let cost = total_cost(pretend_user_input)?; if cost > tokens { println!("You can't afford that many!"); @@ -23,7 +23,7 @@ fn main() { pub fn total_cost(item_quantity: &str) -> Result { let processing_fee = 1; let cost_per_item = 5; - let qty = try!(item_quantity.parse::()); + let qty = item_quantity.parse::()?; Ok(qty * cost_per_item + processing_fee) } @@ -45,23 +45,18 @@ pub fn total_cost(item_quantity: &str) -> Result { -// Since the `try!` macro returns an `Err` early if the thing it's trying to -// do fails, you can only use the `try!` macro in functions that have a +// Since the `?` operator returns an `Err` early if the thing it's trying to +// do fails, you can only use the `?` operator in functions that have a // `Result` as their return type. -// The error that you get if you run this code is: +// Hence the error that you get if you run this code is: // ``` -// error: mismatched types: -// expected `()`, -// found `std::result::Result<_, _>` +// error[E0277]: the `?` operator can only be used in a function that returns `Result` (or another type that implements `std::ops::Try`) // ``` -// which is saying that the expected return type of the `main` function is -// the empty tuple, but we tried to return a `Result`-- and that's happening -// in the implementation of `try!`. The `main` function never has a return type, -// so we have to use another way of handling a `Result` within `main`. +// So we have to use another way of handling a `Result` within `main`. // Decide what we should do if `pretend_user_input` has a string value that does -// not parse to an integer, and implement that instead of calling the `try!` -// macro. +// not parse to an integer, and implement that instead of using the `?` +// operator. diff --git a/error_handling/errorsn.rs b/error_handling/errorsn.rs index ee1179d..dfca1b9 100644 --- a/error_handling/errorsn.rs +++ b/error_handling/errorsn.rs @@ -115,21 +115,21 @@ impl error::Error for CreationError { // Next hint: There are three places in `read_and_validate` that we call a // function that returns a `Result` (that is, the functions might fail). -// Wrap those calls in a `try!` macro call so that we return immediately from +// Apply the `?` operator on those calls so that we return immediately from // `read_and_validate` if those function calls fail. -// Another hint: under the hood, the `try!` macro calls `From::from` +// Another hint: under the hood, the `?` operator calls `From::from` // on the error value to convert it to a boxed trait object, a Box, // which is polymorphic-- that means that lots of different kinds of errors // can be returned from the same function because all errors act the same // since they all implement the `error::Error` trait. // Check out this section of the book: -// https://doc.rust-lang.org/stable/book/error-handling.html#standard-library-traits-used-for-error-handling +// https://doc.rust-lang.org/stable/book/second-edition/ch09-02-recoverable-errors-with-result.html#a-shortcut-for-propagating-errors- -// Another another hint: Note that because the `try!` macro returns +// Another another hint: Note that because the `?` operator returns // the *unwrapped* value in the `Ok` case, if we want to return a `Result` from // `read_and_validate` for *its* success case, we'll have to rewrap a value -// that we got from the return value of a `try!` call in an `Ok`-- this will +// that we got from the return value of a `?`ed call in an `Ok`-- this will // look like `Ok(something)`. // Another another another hint: `Result`s must be "used", that is, you'll From e536a72f06ea80555507166845394822d604137a Mon Sep 17 00:00:00 2001 From: Mateus Costa Date: Thu, 24 May 2018 23:02:05 +0200 Subject: [PATCH 02/15] [#83] improve README to edit locally --- README.md | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/README.md b/README.md index e673184..7361bd6 100644 --- a/README.md +++ b/README.md @@ -19,6 +19,17 @@ can now click on the links below to load the exercises in the rust playground! There are infinite correct answers-- the exercises are sometimes left very open-ended. Scroll down in the playground to find comments that have hints. +### To do these exercises in your local environment and execute them online afterwards: + +* clone the repo to your local environment: `git clone git@github.com:rustlings/rustlings.git` +* edit the rustling that you want, per example `variables/variables1.rs` +* run `cargo run` in the project folder +* you will notice that you README file was modified and now it has the new content of the file that you edited +* click in the new URL in the README and you will redirect to the rust playground and the whole file content it will be loaded +* to execute in the rust playground, just click on `run` + +### Need help? + If you need more help or would like to compare solutions, you can ask in [#rust-beginners on irc.mozilla.org](https://chat.mibbit.com/?server=irc.mozilla.org&channel=%23rust-beginners ), the [user forum](https://users.rust-lang.org/), or [the subreddit](https://reddit.com/r/rust). If an From e48a1a063d591d6293b2ae2193ab5e5aca603ffa Mon Sep 17 00:00:00 2001 From: Lisa Kosiachenko Date: Fri, 20 Jul 2018 11:39:49 -0700 Subject: [PATCH 03/15] update old book references to the second edition of the book --- error_handling/errors2.rs | 2 +- error_handling/errorsn.rs | 2 +- primitive_types/primitive_types3.rs | 7 ++++--- primitive_types/primitive_types4.rs | 8 ++++---- primitive_types/primitive_types5.rs | 8 ++++---- primitive_types/primitive_types6.rs | 5 +++-- standard_library_types/iterator3.rs | 6 ++++-- threads/threads1.rs | 2 +- 8 files changed, 22 insertions(+), 18 deletions(-) diff --git a/error_handling/errors2.rs b/error_handling/errors2.rs index 306eeba..15c21c8 100644 --- a/error_handling/errors2.rs +++ b/error_handling/errors2.rs @@ -68,5 +68,5 @@ mod tests { // `Err(something)`. This pattern is very common in Rust, though, so there's // a `?` operator that does pretty much what you would make that match statement // do for you! Take a look at this section of the Error Handling chapter: -// https://doc.rust-lang.org/book/second-edition/ch09-02-recoverable-errors-with-result.html#a-shortcut-for-propagating-errors- +// https://doc.rust-lang.org/stable/book/second-edition/ch09-02-recoverable-errors-with-result.html#a-shortcut-for-propagating-errors-the--operator // and give it a try! diff --git a/error_handling/errorsn.rs b/error_handling/errorsn.rs index dfca1b9..15c6cd5 100644 --- a/error_handling/errorsn.rs +++ b/error_handling/errorsn.rs @@ -124,7 +124,7 @@ impl error::Error for CreationError { // can be returned from the same function because all errors act the same // since they all implement the `error::Error` trait. // Check out this section of the book: -// https://doc.rust-lang.org/stable/book/second-edition/ch09-02-recoverable-errors-with-result.html#a-shortcut-for-propagating-errors- +// https://doc.rust-lang.org/stable/book/second-edition/ch09-02-recoverable-errors-with-result.html#a-shortcut-for-propagating-errors-the--operator // Another another hint: Note that because the `?` operator returns // the *unwrapped* value in the `Ok` case, if we want to return a `Result` from diff --git a/primitive_types/primitive_types3.rs b/primitive_types/primitive_types3.rs index a2f9b3b..7ce2226 100644 --- a/primitive_types/primitive_types3.rs +++ b/primitive_types/primitive_types3.rs @@ -39,8 +39,9 @@ fn main() { // There's a shorthand to initialize Arrays with a certain size that does not -// require you to type in 100 items (but you certainly can if you want!) -// Check out the Primitive Types -> Arrays section of the book: -// https://doc.rust-lang.org/stable/book/second-edition/ch03-02-data-types.html#arrays +// require you to type in 100 items (but you certainly can if you want!). +// For example, you can do: +// let array = ["Are we there yet?"; 10]; + // Bonus: what are some other things you could have that would return true // for `a.len() >= 100`? diff --git a/primitive_types/primitive_types4.rs b/primitive_types/primitive_types4.rs index c20b63b..7dc9e47 100644 --- a/primitive_types/primitive_types4.rs +++ b/primitive_types/primitive_types4.rs @@ -38,12 +38,12 @@ fn main() { -// Take a look at the Primitive Types -> Slices section of the book: -// http://doc.rust-lang.org/stable/book/primitive-types.html#slices +// Take a look at the Understanding Ownership -> Slices -> Other Slices section of the book: +// https://doc.rust-lang.org/stable/book/second-edition/ch04-03-slices.html#other-slices // and use the starting and ending indices of the items in the Array // that you want to end up in the slice. // If you're curious why the right hand of the `==` comparison does not // have an ampersand for a reference since the left hand side is a -// reference, take a look at the Deref coercions chapter: -// http://doc.rust-lang.org/stable/book/deref-coercions.html +// reference, take a look at the Deref coercions section of the book: +// https://doc.rust-lang.org/stable/book/second-edition/ch15-02-deref.html#implicit-deref-coercions-with-functions-and-methods diff --git a/primitive_types/primitive_types5.rs b/primitive_types/primitive_types5.rs index 14c2fd2..4045e78 100644 --- a/primitive_types/primitive_types5.rs +++ b/primitive_types/primitive_types5.rs @@ -38,8 +38,8 @@ fn main() { -// Take a look at the Primitive Types -> Tuples section of the book: -// http://doc.rust-lang.org/stable/book/primitive-types.html#tuples -// Particularly the part about "destructuring lets". You'll need to -// make a pattern to bind `name` and `age` to the appropriate parts +// Take a look at the Data Types -> The Tuple Type section of the book: +// https://doc.rust-lang.org/stable/book/second-edition/ch03-02-data-types.html#the-tuple-type +// Particularly the part about destructuring (second to last example in the section). +// You'll need to make a pattern to bind `name` and `age` to the appropriate parts // of the tuple. You can do it!! diff --git a/primitive_types/primitive_types6.rs b/primitive_types/primitive_types6.rs index d016642..439a56b 100644 --- a/primitive_types/primitive_types6.rs +++ b/primitive_types/primitive_types6.rs @@ -39,6 +39,7 @@ fn main() { // While you could use a destructuring `let` for the tuple here, try -// indexing into it instead, as explained here: -// http://doc.rust-lang.org/stable/book/primitive-types.html#tuple-indexing +// indexing into it instead, as explained in the last example of the +// Data Types -> The Tuple Type section of the book: +// https://doc.rust-lang.org/stable/book/second-edition/ch03-02-data-types.html#the-tuple-type // Now you have another tool in your toolbox! diff --git a/standard_library_types/iterator3.rs b/standard_library_types/iterator3.rs index e973ac6..1d2e135 100644 --- a/standard_library_types/iterator3.rs +++ b/standard_library_types/iterator3.rs @@ -114,7 +114,8 @@ mod tests { -// Minor hint: In each of the two cases in the match in main, you can create x with either a 'turbofish' or by hinting the type of x to the compiler. You may try both. +// Minor hint: In each of the two cases in the match in main, you can create x with either +// a 'turbofish' or by hinting the type of x to the compiler. You may try both. @@ -142,4 +143,5 @@ mod tests { -// Major hint: Have a look at the Iter trait and at the explanation of its collect function. Especially the part about Result is interesting. +// Major hint: Have a look at the Iter trait and at the explanation of its collect function. +// Especially the part about Result is interesting. diff --git a/threads/threads1.rs b/threads/threads1.rs index b4a5dc9..4f9aa89 100644 --- a/threads/threads1.rs +++ b/threads/threads1.rs @@ -45,7 +45,7 @@ fn main() { // to **immutable** data. But we want to *change* the number of `jobs_completed` // so we'll need to also use another type that will only allow one thread to // mutate the data at a time. Take a look at this section of the book: -// https://doc.rust-lang.org/stable/book/concurrency.html#safe-shared-mutable-state +// https://doc.rust-lang.org/stable/book/second-edition/ch16-03-shared-state.html#atomic-reference-counting-with-arct // and keep scrolling if you'd like more hints :) From 7edb43ed19a73be2596ef5ca8dca799c0a2604b1 Mon Sep 17 00:00:00 2001 From: Lisa Kosiachenko Date: Fri, 20 Jul 2018 15:52:57 -0700 Subject: [PATCH 04/15] Regenerate README --- README.md | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/README.md b/README.md index e673184..bbe0010 100644 --- a/README.md +++ b/README.md @@ -53,10 +53,10 @@ Language](https://doc.rust-lang.org/book/second-edition/ch03-02-data-types.html) - ["primitive_types1.rs"](https://play.rust-lang.org/?code=%2F%2F+primitive_types1.rs%0A%2F%2F+Fill+in+the+rest+of+the+line+that+has+code+missing%21%0A%2F%2F+No+hints%2C+there%27s+no+tricks%2C+just+get+used+to+typing+these+%3A%29%0A%0Afn+main%28%29+%7B%0A++++%2F%2F+Booleans+%28%60bool%60%29%0A%0A++++let+is_morning+%3D+true%3B%0A++++if+is_morning+%7B%0A++++++++println%21%28%22Good+morning%21%22%29%3B%0A++++%7D%0A%0A++++let+%2F%2F+Finish+the+rest+of+this+line+like+the+example%21+Or+make+it+be+false%21%0A++++if+is_evening+%7B%0A++++++++println%21%28%22Good+evening%21%22%29%3B%0A++++%7D%0A%7D%0A) - ["primitive_types2.rs"](https://play.rust-lang.org/?code=%2F%2F+primitive_types2.rs%0A%2F%2F+Fill+in+the+rest+of+the+line+that+has+code+missing%21%0A%2F%2F+No+hints%2C+there%27s+no+tricks%2C+just+get+used+to+typing+these+%3A%29%0A%0Afn+main%28%29+%7B%0A++++%2F%2F+Characters+%28%60char%60%29%0A%0A++++let+my_first_initial+%3D+%27C%27%3B%0A++++if+my_first_initial.is_alphabetic%28%29+%7B%0A++++++++println%21%28%22Alphabetical%21%22%29%3B%0A++++%7D+else+if+my_first_initial.is_numeric%28%29+%7B%0A++++++++println%21%28%22Numerical%21%22%29%3B%0A++++%7D+else+%7B%0A++++++++println%21%28%22Neither+alphabetic+nor+numeric%21%22%29%3B%0A++++%7D%0A%0A++++let+%2F%2F+Finish+this+line+like+the+example%21+What%27s+your+favorite+character%3F%0A++++%2F%2F+Try+a+letter%2C+try+a+number%2C+try+a+special+character%2C+try+a+character%0A++++%2F%2F+from+a+different+language+than+your+own%2C+try+an+emoji%21%0A++++if+your_character.is_alphabetic%28%29+%7B%0A++++++++println%21%28%22Alphabetical%21%22%29%3B%0A++++%7D+else+if+your_character.is_numeric%28%29+%7B%0A++++++++println%21%28%22Numerical%21%22%29%3B%0A++++%7D+else+%7B%0A++++++++println%21%28%22Neither+alphabetic+nor+numeric%21%22%29%3B%0A++++%7D%0A%7D%0A) -- ["primitive_types3.rs"](https://play.rust-lang.org/?code=%2F%2F+primitive_types3.rs%0A%2F%2F+Create+an+array+with+at+least+100+elements+in+it+where+the+%3F%3F%3F+is.+%0A%2F%2F+Scroll+down+for+hints%21%0A%0Afn+main%28%29+%7B%0A++++let+a+%3D+%3F%3F%3F%0A%0A++++if+a.len%28%29+%3E%3D+100+%7B%0A++++++++println%21%28%22Wow%2C+that%27s+a+big+array%21%22%29%3B%0A++++%7D+else+%7B%0A++++++++println%21%28%22Meh%2C+I+eat+arrays+like+that+for+breakfast.%22%29%3B%0A++++%7D%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+There%27s+a+shorthand+to+initialize+Arrays+with+a+certain+size+that+does+not+%0A%2F%2F+require+you+to+type+in+100+items+%28but+you+certainly+can+if+you+want%21%29%0A%2F%2F+Check+out+the+Primitive+Types+-%3E+Arrays+section+of+the+book%3A%0A%2F%2F+https%3A%2F%2Fdoc.rust-lang.org%2Fstable%2Fbook%2Fsecond-edition%2Fch03-02-data-types.html%23arrays%0A%2F%2F+Bonus%3A+what+are+some+other+things+you+could+have+that+would+return+true%0A%2F%2F+for+%60a.len%28%29+%3E%3D+100%60%3F%0A) -- ["primitive_types4.rs"](https://play.rust-lang.org/?code=%2F%2F+primitive_types4.rs%0A%2F%2F+Get+a+slice+out+of+Array+a+where+the+%3F%3F%3F+is+so+that+the+%60if%60+statement%0A%2F%2F+returns+true.+Scroll+down+for+hints%21%21%0A%0Afn+main%28%29+%7B%0A++++let+a+%3D+%5B1%2C+2%2C+3%2C+4%2C+5%5D%3B%0A%0A++++let+nice_slice+%3D+%3F%3F%3F%0A%0A++++if+nice_slice+%3D%3D+%5B2%2C+3%2C+4%5D+%7B%0A++++++++println%21%28%22Nice+slice%21%22%29%3B%0A++++%7D+else+%7B%0A++++++++println%21%28%22Not+quite+what+I+was+expecting...+I+see%3A+%7B%3A%3F%7D%22%2C+nice_slice%29%3B%0A++++%7D%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+Take+a+look+at+the+Primitive+Types+-%3E+Slices+section+of+the+book%3A%0A%2F%2F+http%3A%2F%2Fdoc.rust-lang.org%2Fstable%2Fbook%2Fprimitive-types.html%23slices%0A%2F%2F+and+use+the+starting+and+ending+indices+of+the+items+in+the+Array%0A%2F%2F+that+you+want+to+end+up+in+the+slice.%0A%0A%2F%2F+If+you%27re+curious+why+the+right+hand+of+the+%60%3D%3D%60+comparison+does+not%0A%2F%2F+have+an+ampersand+for+a+reference+since+the+left+hand+side+is+a%0A%2F%2F+reference%2C+take+a+look+at+the+Deref+coercions+chapter%3A%0A%2F%2F+http%3A%2F%2Fdoc.rust-lang.org%2Fstable%2Fbook%2Fderef-coercions.html%0A) -- ["primitive_types5.rs"](https://play.rust-lang.org/?code=%2F%2F+primitive_types5.rs%0A%2F%2F+Destructure+the+%60cat%60+tuple+so+that+the+println+will+work.%0A%2F%2F+Scroll+down+for+hints%21%0A%0Afn+main%28%29+%7B%0A++++let+cat+%3D+%28%22Furry+McFurson%22%2C+3.5%29%3B%0A++++let+%2F*+your+pattern+here+*%2F+%3D+cat%3B%0A%0A++++println%21%28%22%7B%7D+is+%7B%7D+years+old.%22%2C+name%2C+age%29%3B%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+Take+a+look+at+the+Primitive+Types+-%3E+Tuples+section+of+the+book%3A%0A%2F%2F+http%3A%2F%2Fdoc.rust-lang.org%2Fstable%2Fbook%2Fprimitive-types.html%23tuples%0A%2F%2F+Particularly+the+part+about+%22destructuring+lets%22.+You%27ll+need+to%0A%2F%2F+make+a+pattern+to+bind+%60name%60+and+%60age%60+to+the+appropriate+parts%0A%2F%2F+of+the+tuple.+You+can+do+it%21%21%0A) -- ["primitive_types6.rs"](https://play.rust-lang.org/?code=%2F%2F+primitive_types6.rs%0A%2F%2F+Use+a+tuple+index+to+access+the+second+element+of+%60numbers%60.%0A%2F%2F+You+can+put+this+right+into+the+%60println%21%60+where+the+%3F%3F%3F+is.%0A%2F%2F+Scroll+down+for+hints%21%0A%0Afn+main%28%29+%7B%0A++++let+numbers+%3D+%281%2C+2%2C+3%29%3B%0A++++println%21%28%22The+second+number+is+%7B%7D%22%2C+%3F%3F%3F%29%3B%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+While+you+could+use+a+destructuring+%60let%60+for+the+tuple+here%2C+try+%0A%2F%2F+indexing+into+it+instead%2C+as+explained+here%3A%0A%2F%2F+http%3A%2F%2Fdoc.rust-lang.org%2Fstable%2Fbook%2Fprimitive-types.html%23tuple-indexing%0A%2F%2F+Now+you+have+another+tool+in+your+toolbox%21%0A) +- ["primitive_types3.rs"](https://play.rust-lang.org/?code=%2F%2F+primitive_types3.rs%0A%2F%2F+Create+an+array+with+at+least+100+elements+in+it+where+the+%3F%3F%3F+is.+%0A%2F%2F+Scroll+down+for+hints%21%0A%0Afn+main%28%29+%7B%0A++++let+a+%3D+%3F%3F%3F%0A%0A++++if+a.len%28%29+%3E%3D+100+%7B%0A++++++++println%21%28%22Wow%2C+that%27s+a+big+array%21%22%29%3B%0A++++%7D+else+%7B%0A++++++++println%21%28%22Meh%2C+I+eat+arrays+like+that+for+breakfast.%22%29%3B%0A++++%7D%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+There%27s+a+shorthand+to+initialize+Arrays+with+a+certain+size+that+does+not+%0A%2F%2F+require+you+to+type+in+100+items+%28but+you+certainly+can+if+you+want%21%29.%0A%2F%2F+For+example%2C+you+can+do%3A%0A%2F%2F+let+array+%3D+%5B%22Are+we+there+yet%3F%22%3B+10%5D%3B%0A%0A%2F%2F+Bonus%3A+what+are+some+other+things+you+could+have+that+would+return+true%0A%2F%2F+for+%60a.len%28%29+%3E%3D+100%60%3F%0A) +- ["primitive_types4.rs"](https://play.rust-lang.org/?code=%2F%2F+primitive_types4.rs%0A%2F%2F+Get+a+slice+out+of+Array+a+where+the+%3F%3F%3F+is+so+that+the+%60if%60+statement%0A%2F%2F+returns+true.+Scroll+down+for+hints%21%21%0A%0Afn+main%28%29+%7B%0A++++let+a+%3D+%5B1%2C+2%2C+3%2C+4%2C+5%5D%3B%0A%0A++++let+nice_slice+%3D+%3F%3F%3F%0A%0A++++if+nice_slice+%3D%3D+%5B2%2C+3%2C+4%5D+%7B%0A++++++++println%21%28%22Nice+slice%21%22%29%3B%0A++++%7D+else+%7B%0A++++++++println%21%28%22Not+quite+what+I+was+expecting...+I+see%3A+%7B%3A%3F%7D%22%2C+nice_slice%29%3B%0A++++%7D%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+Take+a+look+at+the+Understanding+Ownership+-%3E+Slices+-%3E+Other+Slices+section+of+the+book%3A%0A%2F%2F+https%3A%2F%2Fdoc.rust-lang.org%2Fstable%2Fbook%2Fsecond-edition%2Fch04-03-slices.html%23other-slices%0A%2F%2F+and+use+the+starting+and+ending+indices+of+the+items+in+the+Array%0A%2F%2F+that+you+want+to+end+up+in+the+slice.%0A%0A%2F%2F+If+you%27re+curious+why+the+right+hand+of+the+%60%3D%3D%60+comparison+does+not%0A%2F%2F+have+an+ampersand+for+a+reference+since+the+left+hand+side+is+a%0A%2F%2F+reference%2C+take+a+look+at+the+Deref+coercions+section+of+the+book%3A%0A%2F%2F+https%3A%2F%2Fdoc.rust-lang.org%2Fstable%2Fbook%2Fsecond-edition%2Fch15-02-deref.html%23implicit-deref-coercions-with-functions-and-methods%0A) +- ["primitive_types5.rs"](https://play.rust-lang.org/?code=%2F%2F+primitive_types5.rs%0A%2F%2F+Destructure+the+%60cat%60+tuple+so+that+the+println+will+work.%0A%2F%2F+Scroll+down+for+hints%21%0A%0Afn+main%28%29+%7B%0A++++let+cat+%3D+%28%22Furry+McFurson%22%2C+3.5%29%3B%0A++++let+%2F*+your+pattern+here+*%2F+%3D+cat%3B%0A%0A++++println%21%28%22%7B%7D+is+%7B%7D+years+old.%22%2C+name%2C+age%29%3B%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+Take+a+look+at+the+Data+Types+-%3E+The+Tuple+Type+section+of+the+book%3A%0A%2F%2F+https%3A%2F%2Fdoc.rust-lang.org%2Fstable%2Fbook%2Fsecond-edition%2Fch03-02-data-types.html%23the-tuple-type%0A%2F%2F+Particularly+the+part+about+destructuring+%28second+to+last+example+in+the+section%29.+%0A%2F%2F+You%27ll+need+to+make+a+pattern+to+bind+%60name%60+and+%60age%60+to+the+appropriate+parts%0A%2F%2F+of+the+tuple.+You+can+do+it%21%21%0A) +- ["primitive_types6.rs"](https://play.rust-lang.org/?code=%2F%2F+primitive_types6.rs%0A%2F%2F+Use+a+tuple+index+to+access+the+second+element+of+%60numbers%60.%0A%2F%2F+You+can+put+this+right+into+the+%60println%21%60+where+the+%3F%3F%3F+is.%0A%2F%2F+Scroll+down+for+hints%21%0A%0Afn+main%28%29+%7B%0A++++let+numbers+%3D+%281%2C+2%2C+3%29%3B%0A++++println%21%28%22The+second+number+is+%7B%7D%22%2C+%3F%3F%3F%29%3B%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+While+you+could+use+a+destructuring+%60let%60+for+the+tuple+here%2C+try+%0A%2F%2F+indexing+into+it+instead%2C+as+explained+in+the+last+example+of+the+%0A%2F%2F+Data+Types+-%3E+The+Tuple+Type+section+of+the+book%3A%0A%2F%2F+https%3A%2F%2Fdoc.rust-lang.org%2Fstable%2Fbook%2Fsecond-edition%2Fch03-02-data-types.html%23the-tuple-type%0A%2F%2F+Now+you+have+another+tool+in+your+toolbox%21%0A) ### Tests @@ -138,9 +138,9 @@ relevant. - ["option1.rs"](https://play.rust-lang.org/?code=%2F%2F+option1.rs%0A%2F%2F+This+example+panics+because+the+second+time+it+calls+%60pop%60%2C+the+%60vec%60%0A%2F%2F+is+empty%2C+so+%60pop%60+returns+%60None%60%2C+and+%60unwrap%60+panics+if+it%27s+called%0A%2F%2F+on+%60None%60.+Handle+this+in+a+more+graceful+way+than+calling+%60unwrap%60%21%0A%2F%2F+Scroll+down+for+hints+%3A%29%0A%0Afn+main%28%29+%7B%0A++++let+mut+list+%3D+vec%21%5B3%5D%3B%0A%0A++++let+last+%3D+list.pop%28%29.unwrap%28%29%3B%0A++++println%21%28%22The+last+item+in+the+list+is+%7B%3A%3F%7D%22%2C+last%29%3B%0A%0A++++let+second_to_last+%3D+list.pop%28%29.unwrap%28%29%3B%0A++++println%21%28%22The+second-to-last+item+in+the+list+is+%7B%3A%3F%7D%22%2C+second_to_last%29%3B%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+Try+using+a+%60match%60+statement+where+the+arms+are+%60Some%28thing%29%60+and+%60None%60.%0A%2F%2F+Or+set+a+default+value+to+print+out+if+you+get+%60None%60+by+using+the%0A%2F%2F+function+%60unwrap_or%60.%0A%2F%2F+Or+use+an+%60if+let%60+statement+on+the+result+of+%60pop%28%29%60+to+both+destructure%0A%2F%2F+a+%60Some%60+value+and+only+print+out+something+if+we+have+a+value%21%0A) - ["result1.rs"](https://play.rust-lang.org/?code=%2F%2F+result1.rs%0A%2F%2F+Make+this+test+pass%21+Scroll+down+for+hints+%3A%29%0A%0A%23%5Bderive%28PartialEq%2CDebug%29%5D%0Astruct+PositiveNonzeroInteger%28u64%29%3B%0A%0A%23%5Bderive%28PartialEq%2CDebug%29%5D%0Aenum+CreationError+%7B%0A++++Negative%2C%0A++++Zero%2C%0A%7D%0A%0Aimpl+PositiveNonzeroInteger+%7B%0A++++fn+new%28value%3A+i64%29+-%3E+Result%3CPositiveNonzeroInteger%2C+CreationError%3E+%7B%0A++++++++Ok%28PositiveNonzeroInteger%28value+as+u64%29%29%0A++++%7D%0A%7D%0A%0A%23%5Btest%5D%0Afn+test_creation%28%29+%7B%0A++++assert%21%28PositiveNonzeroInteger%3A%3Anew%2810%29.is_ok%28%29%29%3B%0A++++assert_eq%21%28Err%28CreationError%3A%3ANegative%29%2C+PositiveNonzeroInteger%3A%3Anew%28-10%29%29%3B%0A++++assert_eq%21%28Err%28CreationError%3A%3AZero%29%2C+PositiveNonzeroInteger%3A%3Anew%280%29%29%3B%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+%60PositiveNonzeroInteger%3A%3Anew%60+is+always+creating+a+new+instance+and+returning+an+%60Ok%60+result.%0A%2F%2F+It+should+be+doing+some+checking%2C+returning+an+%60Err%60+result+if+those+checks+fail%2C+and+only%0A%2F%2F+returning+an+%60Ok%60+result+if+those+checks+determine+that+everything+is...+okay+%3A%29%0A) - ["errors1.rs"](https://play.rust-lang.org/?code=%2F%2F+errors1.rs%0A%2F%2F+This+function+refuses+to+generate+text+to+be+printed+on+a+nametag+if%0A%2F%2F+you+pass+it+an+empty+string.+It%27d+be+nicer+if+it+explained+what+the+problem%0A%2F%2F+was%2C+instead+of+just+sometimes+returning+%60None%60.+The+2nd+test+currently%0A%2F%2F+does+not+compile+or+pass%2C+but+it+illustrates+the+behavior+we+would+like%0A%2F%2F+this+function+to+have.%0A%2F%2F+Scroll+down+for+hints%21%21%21%0A%0Apub+fn+generate_nametag_text%28name%3A+String%29+-%3E+Option%3CString%3E+%7B%0A++++if+name.len%28%29+%3E+0+%7B%0A++++++++Some%28format%21%28%22Hi%21+My+name+is+%7B%7D%22%2C+name%29%29%0A++++%7D+else+%7B%0A++++++++%2F%2F+Empty+names+aren%27t+allowed.%0A++++++++None%0A++++%7D%0A%7D%0A%0A%23%5Bcfg%28test%29%5D%0Amod+tests+%7B%0A++++use+super%3A%3A*%3B%0A%0A++++%2F%2F+This+test+passes+initially+if+you+comment+out+the+2nd+test.%0A++++%2F%2F+You%27ll+need+to+update+what+this+test+expects+when+you+change%0A++++%2F%2F+the+function+under+test%21%0A++++%23%5Btest%5D%0A++++fn+generates_nametag_text_for_a_nonempty_name%28%29+%7B%0A++++++++assert_eq%21%28%0A++++++++++++generate_nametag_text%28%22Beyonc%C3%A9%22.into%28%29%29%2C%0A++++++++++++Some%28%22Hi%21+My+name+is+Beyonc%C3%A9%22.into%28%29%29%0A++++++++%29%3B%0A++++%7D%0A%0A++++%23%5Btest%5D%0A++++fn+explains_why_generating_nametag_text_fails%28%29+%7B%0A++++++++assert_eq%21%28%0A++++++++++++generate_nametag_text%28%22%22.into%28%29%29%2C%0A++++++++++++Err%28%22%60name%60+was+empty%3B+it+must+be+nonempty.%22.into%28%29%29%0A++++++++%29%3B%0A++++%7D%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+%60Err%60+is+one+of+the+variants+of+%60Result%60%2C+so+what+the+2nd+test+is+saying%0A%2F%2F+is+that+%60generate_nametag_text%60+should+return+a+%60Result%60+instead+of+an%0A%2F%2F+%60Option%60.%0A%0A%2F%2F+To+make+this+change%2C+you%27ll+need+to%3A%0A%2F%2F+-+update+the+return+type+in+the+function+signature+to+be+a+Result+that%0A%2F%2F+++could+be+the+variants+%60Ok%28String%29%60+and+%60Err%28String%29%60%0A%2F%2F+-+change+the+body+of+the+function+to+return+%60Ok%28stuff%29%60+where+it+currently%0A%2F%2F+++returns+%60Some%28stuff%29%60%0A%2F%2F+-+change+the+body+of+the+function+to+return+%60Err%28error+message%29%60+where+it%0A%2F%2F+++currently+returns+%60None%60%0A%2F%2F+-+change+the+first+test+to+expect+%60Ok%28stuff%29%60+where+it+currently+expects%0A%2F%2F+++%60Some%28stuff%29%60.%0A) -- ["errors2.rs"](https://play.rust-lang.org/?code=%2F%2F+errors2.rs%0A%2F%2F+Say+we%27re+writing+a+game+where+you+can+buy+items+with+tokens.+All+items+cost%0A%2F%2F+5+tokens%2C+and+whenever+you+purchase+items+there+is+a+processing+fee+of+1%0A%2F%2F+token.+A+player+of+the+game+will+type+in+how+many+items+they+want+to+buy%2C%0A%2F%2F+and+the+%60total_cost%60+function+will+calculate+the+total+number+of+tokens.%0A%2F%2F+Since+the+player+typed+in+the+quantity%2C+though%2C+we+get+it+as+a+string--+and%0A%2F%2F+they+might+have+typed+anything%2C+not+just+numbers%21%0A%0A%2F%2F+Right+now%2C+this+function+isn%27t+handling+the+error+case+at+all+%28and+isn%27t%0A%2F%2F+handling+the+success+case+properly+either%29.+What+we+want+to+do+is%3A%0A%2F%2F+if+we+call+the+%60parse%60+function+on+a+string+that+is+not+a+number%2C+that%0A%2F%2F+function+will+return+a+%60ParseIntError%60%2C+and+in+that+case%2C+we+want+to%0A%2F%2F+immediately+return+that+error+from+our+function+and+not+try+to+multiply%0A%2F%2F+and+add.%0A%0A%2F%2F+There+are+at+least+two+ways+to+implement+this+that+are+both+correct--+but%0A%2F%2F+one+is+a+lot+shorter%21+Scroll+down+for+hints+to+both+ways.%0A%0Ause+std%3A%3Anum%3A%3AParseIntError%3B%0A%0Apub+fn+total_cost%28item_quantity%3A+%26str%29+-%3E+Result%3Ci32%2C+ParseIntError%3E+%7B%0A++++let+processing_fee+%3D+1%3B%0A++++let+cost_per_item+%3D+5%3B%0A++++let+qty+%3D+item_quantity.parse%3A%3A%3Ci32%3E%28%29%3B%0A%0A++++Ok%28qty+*+cost_per_item+%2B+processing_fee%29%0A%7D%0A%0A%23%5Bcfg%28test%29%5D%0Amod+tests+%7B%0A++++use+super%3A%3A*%3B%0A%0A++++%23%5Btest%5D%0A++++fn+item_quantity_is_a_valid_number%28%29+%7B%0A++++++++assert_eq%21%28%0A++++++++++++total_cost%28%2234%22%29%2C%0A++++++++++++Ok%28171%29%0A++++++++%29%3B%0A++++%7D%0A%0A++++%23%5Btest%5D%0A++++fn+item_quantity_is_an_invalid_number%28%29+%7B%0A++++++++assert_eq%21%28%0A++++++++++++total_cost%28%22beep+boop%22%29.unwrap_err%28%29.to_string%28%29%2C%0A++++++++++++%22invalid+digit+found+in+string%22%0A++++++++%29%3B%0A++++%7D%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+One+way+to+handle+this+is+using+a+%60match%60+statement+on%0A%2F%2F+%60item_quantity.parse%3A%3A%3Ci32%3E%28%29%60+where+the+cases+are+%60Ok%28something%29%60+and%0A%2F%2F+%60Err%28something%29%60.+This+pattern+is+very+common+in+Rust%2C+though%2C+so+there%27s%0A%2F%2F+a+%60%3F%60+operator+that+does+pretty+much+what+you+would+make+that+match+statement%0A%2F%2F+do+for+you%21+Take+a+look+at+this+section+of+the+Error+Handling+chapter%3A%0A%2F%2F+https%3A%2F%2Fdoc.rust-lang.org%2Fbook%2Fsecond-edition%2Fch09-02-recoverable-errors-with-result.html%23a-shortcut-for-propagating-errors-%0A%2F%2F+and+give+it+a+try%21%0A) +- ["errors2.rs"](https://play.rust-lang.org/?code=%2F%2F+errors2.rs%0A%2F%2F+Say+we%27re+writing+a+game+where+you+can+buy+items+with+tokens.+All+items+cost%0A%2F%2F+5+tokens%2C+and+whenever+you+purchase+items+there+is+a+processing+fee+of+1%0A%2F%2F+token.+A+player+of+the+game+will+type+in+how+many+items+they+want+to+buy%2C%0A%2F%2F+and+the+%60total_cost%60+function+will+calculate+the+total+number+of+tokens.%0A%2F%2F+Since+the+player+typed+in+the+quantity%2C+though%2C+we+get+it+as+a+string--+and%0A%2F%2F+they+might+have+typed+anything%2C+not+just+numbers%21%0A%0A%2F%2F+Right+now%2C+this+function+isn%27t+handling+the+error+case+at+all+%28and+isn%27t%0A%2F%2F+handling+the+success+case+properly+either%29.+What+we+want+to+do+is%3A%0A%2F%2F+if+we+call+the+%60parse%60+function+on+a+string+that+is+not+a+number%2C+that%0A%2F%2F+function+will+return+a+%60ParseIntError%60%2C+and+in+that+case%2C+we+want+to%0A%2F%2F+immediately+return+that+error+from+our+function+and+not+try+to+multiply%0A%2F%2F+and+add.%0A%0A%2F%2F+There+are+at+least+two+ways+to+implement+this+that+are+both+correct--+but%0A%2F%2F+one+is+a+lot+shorter%21+Scroll+down+for+hints+to+both+ways.%0A%0Ause+std%3A%3Anum%3A%3AParseIntError%3B%0A%0Apub+fn+total_cost%28item_quantity%3A+%26str%29+-%3E+Result%3Ci32%2C+ParseIntError%3E+%7B%0A++++let+processing_fee+%3D+1%3B%0A++++let+cost_per_item+%3D+5%3B%0A++++let+qty+%3D+item_quantity.parse%3A%3A%3Ci32%3E%28%29%3B%0A%0A++++Ok%28qty+*+cost_per_item+%2B+processing_fee%29%0A%7D%0A%0A%23%5Bcfg%28test%29%5D%0Amod+tests+%7B%0A++++use+super%3A%3A*%3B%0A%0A++++%23%5Btest%5D%0A++++fn+item_quantity_is_a_valid_number%28%29+%7B%0A++++++++assert_eq%21%28%0A++++++++++++total_cost%28%2234%22%29%2C%0A++++++++++++Ok%28171%29%0A++++++++%29%3B%0A++++%7D%0A%0A++++%23%5Btest%5D%0A++++fn+item_quantity_is_an_invalid_number%28%29+%7B%0A++++++++assert_eq%21%28%0A++++++++++++total_cost%28%22beep+boop%22%29.unwrap_err%28%29.to_string%28%29%2C%0A++++++++++++%22invalid+digit+found+in+string%22%0A++++++++%29%3B%0A++++%7D%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+One+way+to+handle+this+is+using+a+%60match%60+statement+on%0A%2F%2F+%60item_quantity.parse%3A%3A%3Ci32%3E%28%29%60+where+the+cases+are+%60Ok%28something%29%60+and%0A%2F%2F+%60Err%28something%29%60.+This+pattern+is+very+common+in+Rust%2C+though%2C+so+there%27s%0A%2F%2F+a+%60%3F%60+operator+that+does+pretty+much+what+you+would+make+that+match+statement%0A%2F%2F+do+for+you%21+Take+a+look+at+this+section+of+the+Error+Handling+chapter%3A%0A%2F%2F+https%3A%2F%2Fdoc.rust-lang.org%2Fstable%2Fbook%2Fsecond-edition%2Fch09-02-recoverable-errors-with-result.html%23a-shortcut-for-propagating-errors-the--operator%0A%2F%2F+and+give+it+a+try%21%0A) - ["errors3.rs"](https://play.rust-lang.org/?code=%2F%2F+errors3.rs%0A%2F%2F+This+is+a+program+that+is+trying+to+use+a+completed+version+of+the%0A%2F%2F+%60total_cost%60+function+from+the+previous+exercise.+It%27s+not+working+though--%0A%2F%2F+we+can%27t+use+the+%60%3F%60+operator+in+the+%60main%28%29%60+function%21+Why+not%3F%0A%2F%2F+What+should+we+do+instead%3F+Scroll+for+hints%21%0A%0Ause+std%3A%3Anum%3A%3AParseIntError%3B%0A%0Afn+main%28%29+%7B%0A++++let+mut+tokens+%3D+100%3B%0A++++let+pretend_user_input+%3D+%228%22%3B%0A%0A++++let+cost+%3D+total_cost%28pretend_user_input%29%3F%3B%0A%0A++++if+cost+%3E+tokens+%7B%0A++++++++println%21%28%22You+can%27t+afford+that+many%21%22%29%3B%0A++++%7D+else+%7B%0A++++++++tokens+-%3D+cost%3B%0A++++++++println%21%28%22You+now+have+%7B%7D+tokens.%22%2C+tokens%29%3B%0A++++%7D%0A%7D%0A%0Apub+fn+total_cost%28item_quantity%3A+%26str%29+-%3E+Result%3Ci32%2C+ParseIntError%3E+%7B%0A++++let+processing_fee+%3D+1%3B%0A++++let+cost_per_item+%3D+5%3B%0A++++let+qty+%3D+item_quantity.parse%3A%3A%3Ci32%3E%28%29%3F%3B%0A%0A++++Ok%28qty+*+cost_per_item+%2B+processing_fee%29%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+Since+the+%60%3F%60+operator+returns+an+%60Err%60+early+if+the+thing+it%27s+trying+to%0A%2F%2F+do+fails%2C+you+can+only+use+the+%60%3F%60+operator+in+functions+that+have+a%0A%2F%2F+%60Result%60+as+their+return+type.%0A%0A%2F%2F+Hence+the+error+that+you+get+if+you+run+this+code+is%3A%0A%0A%2F%2F+%60%60%60%0A%2F%2F+error%5BE0277%5D%3A+the+%60%3F%60+operator+can+only+be+used+in+a+function+that+returns+%60Result%60+%28or+another+type+that+implements+%60std%3A%3Aops%3A%3ATry%60%29%0A%2F%2F+%60%60%60%0A%0A%2F%2F+So+we+have+to+use+another+way+of+handling+a+%60Result%60+within+%60main%60.%0A%0A%2F%2F+Decide+what+we+should+do+if+%60pretend_user_input%60+has+a+string+value+that+does%0A%2F%2F+not+parse+to+an+integer%2C+and+implement+that+instead+of+using+the+%60%3F%60%0A%2F%2F+operator.%0A) -- ["errorsn.rs"](https://play.rust-lang.org/?code=%2F%2F+errorsn.rs%0A%2F%2F+This+is+a+bigger+error+exercise+than+the+previous+ones%21%0A%2F%2F+You+can+do+it%21+%3A%29%0A%2F%2F%0A%2F%2F+Edit+the+%60read_and_validate%60+function+so+that+it+compiles+and%0A%2F%2F+passes+the+tests...+so+many+things+could+go+wrong%21%0A%2F%2F%0A%2F%2F+-+Reading+from+stdin+could+produce+an+io%3A%3AError%0A%2F%2F+-+Parsing+the+input+could+produce+a+num%3A%3AParseIntError%0A%2F%2F+-+Validating+the+input+could+produce+a+CreationError+%28defined+below%29%0A%2F%2F%0A%2F%2F+How+can+we+lump+these+errors+into+one+general+error%3F+That+is%2C+what%0A%2F%2F+type+goes+where+the+question+marks+are%2C+and+how+do+we+return%0A%2F%2F+that+type+from+the+body+of+read_and_validate%3F%0A%2F%2F%0A%2F%2F+Scroll+down+for+hints+%3A%29%0A%0Ause+std%3A%3Aerror%3B%0Ause+std%3A%3Afmt%3B%0Ause+std%3A%3Aio%3B%0A%0A%2F%2F+PositiveNonzeroInteger+is+a+struct+defined+below+the+tests.%0Afn+read_and_validate%28b%3A+%26mut+io%3A%3ABufRead%29+-%3E+Result%3CPositiveNonzeroInteger%2C+%3F%3F%3F%3E+%7B%0A++++let+mut+line+%3D+String%3A%3Anew%28%29%3B%0A++++b.read_line%28%26mut+line%29%3B%0A++++let+num%3A+i64+%3D+line.trim%28%29.parse%28%29%3B%0A++++let+answer+%3D+PositiveNonzeroInteger%3A%3Anew%28num%29%3B%0A++++answer%0A%7D%0A%0A%2F%2F+This+is+a+test+helper+function+that+turns+a+%26str+into+a+BufReader.%0Afn+test_with_str%28s%3A+%26str%29+-%3E+Result%3CPositiveNonzeroInteger%2C+Box%3Cerror%3A%3AError%3E%3E+%7B%0A++++let+mut+b+%3D+io%3A%3ABufReader%3A%3Anew%28s.as_bytes%28%29%29%3B%0A++++read_and_validate%28%26mut+b%29%0A%7D%0A%0A%23%5Btest%5D%0Afn+test_success%28%29+%7B%0A++++let+x+%3D+test_with_str%28%2242%5Cn%22%29%3B%0A++++assert_eq%21%28PositiveNonzeroInteger%2842%29%2C+x.unwrap%28%29%29%3B%0A%7D%0A%0A%23%5Btest%5D%0Afn+test_not_num%28%29+%7B%0A++++let+x+%3D+test_with_str%28%22eleven+billion%5Cn%22%29%3B%0A++++assert%21%28x.is_err%28%29%29%3B%0A%7D%0A%0A%23%5Btest%5D%0Afn+test_non_positive%28%29+%7B%0A++++let+x+%3D+test_with_str%28%22-40%5Cn%22%29%3B%0A++++assert%21%28x.is_err%28%29%29%3B%0A%7D%0A%0A%23%5Btest%5D%0Afn+test_ioerror%28%29+%7B%0A++++struct+Broken%3B%0A++++impl+io%3A%3ARead+for+Broken+%7B%0A++++++++fn+read%28%26mut+self%2C+_buf%3A+%26mut+%5Bu8%5D%29+-%3E+io%3A%3AResult%3Cusize%3E+%7B%0A++++++++++++Err%28io%3A%3AError%3A%3Anew%28io%3A%3AErrorKind%3A%3ABrokenPipe%2C+%22uh-oh%21%22%29%29%0A++++++++%7D%0A++++%7D%0A++++let+mut+b+%3D+io%3A%3ABufReader%3A%3Anew%28Broken%29%3B%0A++++assert%21%28read_and_validate%28%26mut+b%29.is_err%28%29%29%3B%0A++++assert_eq%21%28%22uh-oh%21%22%2C+read_and_validate%28%26mut+b%29.unwrap_err%28%29.to_string%28%29%29%3B%0A%7D%0A%0A%23%5Bderive%28PartialEq%2CDebug%29%5D%0Astruct+PositiveNonzeroInteger%28u64%29%3B%0A%0Aimpl+PositiveNonzeroInteger+%7B%0A++++fn+new%28value%3A+i64%29+-%3E+Result%3CPositiveNonzeroInteger%2C+CreationError%3E+%7B%0A++++++++if+value+%3D%3D+0+%7B%0A++++++++++++Err%28CreationError%3A%3AZero%29%0A++++++++%7D+else+if+value+%3C+0+%7B%0A++++++++++++Err%28CreationError%3A%3ANegative%29%0A++++++++%7D+else+%7B%0A++++++++++++Ok%28PositiveNonzeroInteger%28value+as+u64%29%29%0A++++++++%7D%0A++++%7D%0A%7D%0A%0A%23%5Btest%5D%0Afn+test_positive_nonzero_integer_creation%28%29+%7B%0A++++assert%21%28PositiveNonzeroInteger%3A%3Anew%2810%29.is_ok%28%29%29%3B%0A++++assert_eq%21%28Err%28CreationError%3A%3ANegative%29%2C+PositiveNonzeroInteger%3A%3Anew%28-10%29%29%3B%0A++++assert_eq%21%28Err%28CreationError%3A%3AZero%29%2C+PositiveNonzeroInteger%3A%3Anew%280%29%29%3B%0A%7D%0A%0A%23%5Bderive%28PartialEq%2CDebug%29%5D%0Aenum+CreationError+%7B%0A++++Negative%2C%0A++++Zero%2C%0A%7D%0A%0Aimpl+fmt%3A%3ADisplay+for+CreationError+%7B%0A++++fn+fmt%28%26self%2C+f%3A+%26mut+fmt%3A%3AFormatter%29+-%3E+fmt%3A%3AResult+%7B%0A++++++++f.write_str%28%28self+as+%26error%3A%3AError%29.description%28%29%29%0A++++%7D%0A%7D%0A%0Aimpl+error%3A%3AError+for+CreationError+%7B%0A++++fn+description%28%26self%29+-%3E+%26str+%7B%0A++++++++match+*self+%7B%0A++++++++++++CreationError%3A%3ANegative+%3D%3E+%22Negative%22%2C%0A++++++++++++CreationError%3A%3AZero+%3D%3E+%22Zero%22%2C%0A++++++++%7D%0A++++%7D%0A%7D%0A%0A%2F%2F+First+hint%3A+To+figure+out+what+type+should+go+where+the+%3F%3F%3F+is%2C+take+a+look%0A%2F%2F+at+the+test+helper+function+%60test_with_str%60%2C+since+it+returns+whatever%0A%2F%2F+%60read_and_validate%60+returns+and%60test_with_str%60+has+its+signature+fully%0A%2F%2F+specified.%0A%0A%2F%2F+Next+hint%3A+There+are+three+places+in+%60read_and_validate%60+that+we+call+a%0A%2F%2F+function+that+returns+a+%60Result%60+%28that+is%2C+the+functions+might+fail%29.%0A%2F%2F+Apply+the+%60%3F%60+operator+on+those+calls+so+that+we+return+immediately+from%0A%2F%2F+%60read_and_validate%60+if+those+function+calls+fail.%0A%0A%2F%2F+Another+hint%3A+under+the+hood%2C+the+%60%3F%60+operator+calls+%60From%3A%3Afrom%60%0A%2F%2F+on+the+error+value+to+convert+it+to+a+boxed+trait+object%2C+a+Box%3Cerror%3A%3AError%3E%2C%0A%2F%2F+which+is+polymorphic--+that+means+that+lot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+- ["errorsn.rs"](https://play.rust-lang.org/?code=%2F%2F+errorsn.rs%0A%2F%2F+This+is+a+bigger+error+exercise+than+the+previous+ones%21%0A%2F%2F+You+can+do+it%21+%3A%29%0A%2F%2F%0A%2F%2F+Edit+the+%60read_and_validate%60+function+so+that+it+compiles+and%0A%2F%2F+passes+the+tests...+so+many+things+could+go+wrong%21%0A%2F%2F%0A%2F%2F+-+Reading+from+stdin+could+produce+an+io%3A%3AError%0A%2F%2F+-+Parsing+the+input+could+produce+a+num%3A%3AParseIntError%0A%2F%2F+-+Validating+the+input+could+produce+a+CreationError+%28defined+below%29%0A%2F%2F%0A%2F%2F+How+can+we+lump+these+errors+into+one+general+error%3F+That+is%2C+what%0A%2F%2F+type+goes+where+the+question+marks+are%2C+and+how+do+we+return%0A%2F%2F+that+type+from+the+body+of+read_and_validate%3F%0A%2F%2F%0A%2F%2F+Scroll+down+for+hints+%3A%29%0A%0Ause+std%3A%3Aerror%3B%0Ause+std%3A%3Afmt%3B%0Ause+std%3A%3Aio%3B%0A%0A%2F%2F+PositiveNonzeroInteger+is+a+struct+defined+below+the+tests.%0Afn+read_and_validate%28b%3A+%26mut+io%3A%3ABufRead%29+-%3E+Result%3CPositiveNonzeroInteger%2C+%3F%3F%3F%3E+%7B%0A++++let+mut+line+%3D+String%3A%3Anew%28%29%3B%0A++++b.read_line%28%26mut+line%29%3B%0A++++let+num%3A+i64+%3D+line.trim%28%29.parse%28%29%3B%0A++++let+answer+%3D+PositiveNonzeroInteger%3A%3Anew%28num%29%3B%0A++++answer%0A%7D%0A%0A%2F%2F+This+is+a+test+helper+function+that+turns+a+%26str+into+a+BufReader.%0Afn+test_with_str%28s%3A+%26str%29+-%3E+Result%3CPositiveNonzeroInteger%2C+Box%3Cerror%3A%3AError%3E%3E+%7B%0A++++let+mut+b+%3D+io%3A%3ABufReader%3A%3Anew%28s.as_bytes%28%29%29%3B%0A++++read_and_validate%28%26mut+b%29%0A%7D%0A%0A%23%5Btest%5D%0Afn+test_success%28%29+%7B%0A++++let+x+%3D+test_with_str%28%2242%5Cn%22%29%3B%0A++++assert_eq%21%28PositiveNonzeroInteger%2842%29%2C+x.unwrap%28%29%29%3B%0A%7D%0A%0A%23%5Btest%5D%0Afn+test_not_num%28%29+%7B%0A++++let+x+%3D+test_with_str%28%22eleven+billion%5Cn%22%29%3B%0A++++assert%21%28x.is_err%28%29%29%3B%0A%7D%0A%0A%23%5Btest%5D%0Afn+test_non_positive%28%29+%7B%0A++++let+x+%3D+test_with_str%28%22-40%5Cn%22%29%3B%0A++++assert%21%28x.is_err%28%29%29%3B%0A%7D%0A%0A%23%5Btest%5D%0Afn+test_ioerror%28%29+%7B%0A++++struct+Broken%3B%0A++++impl+io%3A%3ARead+for+Broken+%7B%0A++++++++fn+read%28%26mut+self%2C+_buf%3A+%26mut+%5Bu8%5D%29+-%3E+io%3A%3AResult%3Cusize%3E+%7B%0A++++++++++++Err%28io%3A%3AError%3A%3Anew%28io%3A%3AErrorKind%3A%3ABrokenPipe%2C+%22uh-oh%21%22%29%29%0A++++++++%7D%0A++++%7D%0A++++let+mut+b+%3D+io%3A%3ABufReader%3A%3Anew%28Broken%29%3B%0A++++assert%21%28read_and_validate%28%26mut+b%29.is_err%28%29%29%3B%0A++++assert_eq%21%28%22uh-oh%21%22%2C+read_and_validate%28%26mut+b%29.unwrap_err%28%29.to_string%28%29%29%3B%0A%7D%0A%0A%23%5Bderive%28PartialEq%2CDebug%29%5D%0Astruct+PositiveNonzeroInteger%28u64%29%3B%0A%0Aimpl+PositiveNonzeroInteger+%7B%0A++++fn+new%28value%3A+i64%29+-%3E+Result%3CPositiveNonzeroInteger%2C+CreationError%3E+%7B%0A++++++++if+value+%3D%3D+0+%7B%0A++++++++++++Err%28CreationError%3A%3AZero%29%0A++++++++%7D+else+if+value+%3C+0+%7B%0A++++++++++++Err%28CreationError%3A%3ANegative%29%0A++++++++%7D+else+%7B%0A++++++++++++Ok%28PositiveNonzeroInteger%28value+as+u64%29%29%0A++++++++%7D%0A++++%7D%0A%7D%0A%0A%23%5Btest%5D%0Afn+test_positive_nonzero_integer_creation%28%29+%7B%0A++++assert%21%28PositiveNonzeroInteger%3A%3Anew%2810%29.is_ok%28%29%29%3B%0A++++assert_eq%21%28Err%28CreationError%3A%3ANegative%29%2C+PositiveNonzeroInteger%3A%3Anew%28-10%29%29%3B%0A++++assert_eq%21%28Err%28CreationError%3A%3AZero%29%2C+PositiveNonzeroInteger%3A%3Anew%280%29%29%3B%0A%7D%0A%0A%23%5Bderive%28PartialEq%2CDebug%29%5D%0Aenum+CreationError+%7B%0A++++Negative%2C%0A++++Zero%2C%0A%7D%0A%0Aimpl+fmt%3A%3ADisplay+for+CreationError+%7B%0A++++fn+fmt%28%26self%2C+f%3A+%26mut+fmt%3A%3AFormatter%29+-%3E+fmt%3A%3AResult+%7B%0A++++++++f.write_str%28%28self+as+%26error%3A%3AError%29.description%28%29%29%0A++++%7D%0A%7D%0A%0Aimpl+error%3A%3AError+for+CreationError+%7B%0A++++fn+description%28%26self%29+-%3E+%26str+%7B%0A++++++++match+*self+%7B%0A++++++++++++CreationError%3A%3ANegative+%3D%3E+%22Negative%22%2C%0A++++++++++++CreationError%3A%3AZero+%3D%3E+%22Zero%22%2C%0A++++++++%7D%0A++++%7D%0A%7D%0A%0A%2F%2F+First+hint%3A+To+figure+out+what+type+should+go+where+the+%3F%3F%3F+is%2C+take+a+look%0A%2F%2F+at+the+test+helper+function+%60test_with_str%60%2C+since+it+returns+whatever%0A%2F%2F+%60read_and_validate%60+returns+and%60test_with_str%60+has+its+signature+fully%0A%2F%2F+specified.%0A%0A%2F%2F+Next+hint%3A+There+are+three+places+in+%60read_and_validate%60+that+we+call+a%0A%2F%2F+function+that+returns+a+%60Result%60+%28that+is%2C+the+functions+might+fail%29.%0A%2F%2F+Apply+the+%60%3F%60+operator+on+those+calls+so+that+we+return+immediately+from%0A%2F%2F+%60read_and_validate%60+if+those+function+calls+fail.%0A%0A%2F%2F+Another+hint%3A+under+the+hood%2C+the+%60%3F%60+operator+calls+%60From%3A%3Afrom%60%0A%2F%2F+on+the+error+value+to+convert+it+to+a+boxed+trait+object%2C+a+Box%3Cerror%3A%3AError%3E%2C%0A%2F%2F+which+is+polymorphic--+that+means+that+lots+of+different+kinds+of+errors%0A%2F%2F+can+be+returned+from+the+same+function+because+all+errors+act+the+same%0A%2F%2F+since+they+all+implement+the+%60error%3A%3AError%60+trait.%0A%2F%2F+Check+out+this+section+of+the+book%3A%0A%2F%2F+https%3A%2F%2Fdoc.rust-lang.org%2Fstable%2Fbook%2Fsecond-edition%2Fch09-02-recoverable-errors-with-result.html%23a-shortcut-for-propagating-errors-the--operator%0A%0A%2F%2F+Another+another+hint%3A+Note+that+because+the+%60%3F%60+operator+returns%0A%2F%2F+the+*unwrapped*+value+in+the+%60Ok%60+case%2C+if+we+want+to+return+a+%60Result%60+from%0A%2F%2F+%60read_and_validate%60+for+*its*+success+case%2C+we%27ll+have+to+rewrap+a+value%0A%2F%2F+that+we+got+from+the+return+value+of+a+%60%3F%60ed+call+in+an+%60Ok%60--+this+will%0A%2F%2F+look+like+%60Ok%28something%29%60.%0A%0A%2F%2F+Another+another+another+hint%3A+%60Result%60s+must+be+%22used%22%2C+that+is%2C+you%27ll%0A%2F%2F+get+a+warning+if+you+don%27t+handle+a+%60Result%60+that+you+get+in+your%0A%2F%2F+function.+Read+more+about+that+in+the+%60std%3A%3Aresult%60+module+docs%3A%0A%2F%2F+https%3A%2F%2Fdoc.rust-lang.org%2Fstd%2Fresult%2F%23results-must-be-used%0A) ### Standard library types @@ -160,7 +160,7 @@ Check out the [Iterators chapter of the book](https://doc.rust-lang.org/book/second-edition/ch13-02-iterators.html) and the [Iterator docs](https://doc.rust-lang.org/stable/std/iter/trait.Iterator.html). -- ["iterator3.rs"](https://play.rust-lang.org/?code=%2F%2F+iterator3.rs%0A%2F%2F+This+is+a+bigger+exercise+than+most+of+the+others%21+You+can+do+it%21%0A%2F%2F+Here+is+your+mission%2C+should+you+choose+to+accept+it%3A%0A%2F%2F+1.+Complete+the+divide+function+to+get+the+first+four+tests+to+pass%0A%2F%2F+2.+Uncomment+the+last+two+tests+and+get+them+to+pass+by+filling+in%0A%2F%2F++++values+for+%60x%60+using+%60division_results%60.%0A%2F%2F+Scroll+down+for+a+minor+hint+for+part+2%2C+and+scroll+down+further+for%0A%2F%2F+a+major+hint.%0A%2F%2F+Have+fun+%3A-%29%0A%0A%23%5Bderive%28Debug%2C+PartialEq%2C+Eq%29%5D%0Apub+enum+DivisionError+%7B%0A++++NotDivisible%28NotDivisibleError%29%2C%0A++++DivideByZero%2C%0A%7D%0A%0A%23%5Bderive%28Debug%2C+PartialEq%2C+Eq%29%5D%0Apub+struct+NotDivisibleError+%7B%0A++++dividend%3A+i32%2C%0A++++divisor%3A+i32%2C%0A%7D%0A%0A%2F%2F+This+function+should+calculate+%60a%60+divided+by+%60b%60+if+%60a%60+is%0A%2F%2F+evenly+divisible+by+b.%0A%2F%2F+Otherwise%2C+it+should+return+a+suitable+error.%0Apub+fn+divide%28a%3A+i32%2C+b%3A+i32%29+-%3E+Result%3Ci32%2C+DivisionError%3E+%7B%0A%7D%0A%0A%23%5Bcfg%28test%29%5D%0Amod+tests+%7B%0A++++use+super%3A%3A*%3B%0A%0A++++%2F%2F+Tests+that+verify+your+%60divide%60+function+implementation%0A++++%23%5Btest%5D%0A++++fn+test_success%28%29+%7B%0A++++++++assert_eq%21%28divide%2881%2C+9%29%2C+Ok%289%29%29%3B%0A++++%7D%0A%0A++++%23%5Btest%5D%0A++++fn+test_not_divisible%28%29+%7B%0A++++++++assert_eq%21%28%0A++++++++++++divide%2881%2C+6%29%2C%0A++++++++++++Err%28DivisionError%3A%3ANotDivisible%28NotDivisibleError%7B%0A++++++++++++++++dividend%3A+81%2C%0A++++++++++++++++divisor%3A+6%0A++++++++++++%7D%29%29%0A++++++++%29%3B%0A++++%7D%0A%0A++++%23%5Btest%5D%0A++++fn+test_divide_by_0%28%29+%7B%0A++++++++assert_eq%21%28divide%2881%2C+0%29%2C+Err%28DivisionError%3A%3ADivideByZero%29%29%3B%0A++++%7D%0A%0A++++%23%5Btest%5D%0A++++fn+test_divide_0_by_something%28%29+%7B%0A++++++++assert_eq%21%28divide%280%2C+81%29%2C+Ok%280%29%29%3B%0A++++%7D%0A%0A++++%2F%2F+Iterator+exercises+using+your+%60divide%60+function%0A++++%2F*%0A++++%23%5Btest%5D%0A++++fn+result_with_list%28%29+%7B%0A++++++++let+numbers+%3D+vec%21%5B27%2C+297%2C+38502%2C+81%5D%3B%0A++++++++let+division_results+%3D+numbers.into_iter%28%29.map%28%7Cn%7C+divide%28n%2C+27%29%29%3B%0A++++++++let+x+%2F%2F...+Fill+in+here%21%0A++++++++assert_eq%21%28format%21%28%22%7B%3A%3F%7D%22%2C+x%29%2C+%22Ok%28%5B1%2C+11%2C+1426%2C+3%5D%29%22%29%3B%0A++++%7D%0A%0A++++%23%5Btest%5D%0A++++fn+list_of_results%28%29+%7B%0A++++++++let+numbers+%3D+vec%21%5B27%2C+297%2C+38502%2C+81%5D%3B%0A++++++++let+division_results+%3D+numbers.into_iter%28%29.map%28%7Cn%7C+divide%28n%2C+27%29%29%3B%0A++++++++let+x+%2F%2F...+Fill+in+here%21%0A++++++++assert_eq%21%28format%21%28%22%7B%3A%3F%7D%22%2C+x%29%2C+%22%5BOk%281%29%2C+Ok%2811%29%2C+Ok%281426%29%2C+Ok%283%29%5D%22%29%3B%0A++++%7D%0A++++*%2F%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+Minor+hint%3A+In+each+of+the+two+cases+in+the+match+in+main%2C+you+can+create+x+with+either+a+%27turbofish%27+or+by+hinting+the+type+of+x+to+the+compiler.+You+may+try+both.%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+Major+hint%3A+Have+a+look+at+the+Iter+trait+and+at+the+explanation+of+its+collect+function.+Especially+the+part+about+Result+is+interesting.%0A) +- ["iterator3.rs"](https://play.rust-lang.org/?code=%2F%2F+iterator3.rs%0A%2F%2F+This+is+a+bigger+exercise+than+most+of+the+others%21+You+can+do+it%21%0A%2F%2F+Here+is+your+mission%2C+should+you+choose+to+accept+it%3A%0A%2F%2F+1.+Complete+the+divide+function+to+get+the+first+four+tests+to+pass%0A%2F%2F+2.+Uncomment+the+last+two+tests+and+get+them+to+pass+by+filling+in%0A%2F%2F++++values+for+%60x%60+using+%60division_results%60.%0A%2F%2F+Scroll+down+for+a+minor+hint+for+part+2%2C+and+scroll+down+further+for%0A%2F%2F+a+major+hint.%0A%2F%2F+Have+fun+%3A-%29%0A%0A%23%5Bderive%28Debug%2C+PartialEq%2C+Eq%29%5D%0Apub+enum+DivisionError+%7B%0A++++NotDivisible%28NotDivisibleError%29%2C%0A++++DivideByZero%2C%0A%7D%0A%0A%23%5Bderive%28Debug%2C+PartialEq%2C+Eq%29%5D%0Apub+struct+NotDivisibleError+%7B%0A++++dividend%3A+i32%2C%0A++++divisor%3A+i32%2C%0A%7D%0A%0A%2F%2F+This+function+should+calculate+%60a%60+divided+by+%60b%60+if+%60a%60+is%0A%2F%2F+evenly+divisible+by+b.%0A%2F%2F+Otherwise%2C+it+should+return+a+suitable+error.%0Apub+fn+divide%28a%3A+i32%2C+b%3A+i32%29+-%3E+Result%3Ci32%2C+DivisionError%3E+%7B%0A%7D%0A%0A%23%5Bcfg%28test%29%5D%0Amod+tests+%7B%0A++++use+super%3A%3A*%3B%0A%0A++++%2F%2F+Tests+that+verify+your+%60divide%60+function+implementation%0A++++%23%5Btest%5D%0A++++fn+test_success%28%29+%7B%0A++++++++assert_eq%21%28divide%2881%2C+9%29%2C+Ok%289%29%29%3B%0A++++%7D%0A%0A++++%23%5Btest%5D%0A++++fn+test_not_divisible%28%29+%7B%0A++++++++assert_eq%21%28%0A++++++++++++divide%2881%2C+6%29%2C%0A++++++++++++Err%28DivisionError%3A%3ANotDivisible%28NotDivisibleError%7B%0A++++++++++++++++dividend%3A+81%2C%0A++++++++++++++++divisor%3A+6%0A++++++++++++%7D%29%29%0A++++++++%29%3B%0A++++%7D%0A%0A++++%23%5Btest%5D%0A++++fn+test_divide_by_0%28%29+%7B%0A++++++++assert_eq%21%28divide%2881%2C+0%29%2C+Err%28DivisionError%3A%3ADivideByZero%29%29%3B%0A++++%7D%0A%0A++++%23%5Btest%5D%0A++++fn+test_divide_0_by_something%28%29+%7B%0A++++++++assert_eq%21%28divide%280%2C+81%29%2C+Ok%280%29%29%3B%0A++++%7D%0A%0A++++%2F%2F+Iterator+exercises+using+your+%60divide%60+function%0A++++%2F*%0A++++%23%5Btest%5D%0A++++fn+result_with_list%28%29+%7B%0A++++++++let+numbers+%3D+vec%21%5B27%2C+297%2C+38502%2C+81%5D%3B%0A++++++++let+division_results+%3D+numbers.into_iter%28%29.map%28%7Cn%7C+divide%28n%2C+27%29%29%3B%0A++++++++let+x+%2F%2F...+Fill+in+here%21%0A++++++++assert_eq%21%28format%21%28%22%7B%3A%3F%7D%22%2C+x%29%2C+%22Ok%28%5B1%2C+11%2C+1426%2C+3%5D%29%22%29%3B%0A++++%7D%0A%0A++++%23%5Btest%5D%0A++++fn+list_of_results%28%29+%7B%0A++++++++let+numbers+%3D+vec%21%5B27%2C+297%2C+38502%2C+81%5D%3B%0A++++++++let+division_results+%3D+numbers.into_iter%28%29.map%28%7Cn%7C+divide%28n%2C+27%29%29%3B%0A++++++++let+x+%2F%2F...+Fill+in+here%21%0A++++++++assert_eq%21%28format%21%28%22%7B%3A%3F%7D%22%2C+x%29%2C+%22%5BOk%281%29%2C+Ok%2811%29%2C+Ok%281426%29%2C+Ok%283%29%5D%22%29%3B%0A++++%7D%0A++++*%2F%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+Minor+hint%3A+In+each+of+the+two+cases+in+the+match+in+main%2C+you+can+create+x+with+either+%0A%2F%2F+a+%27turbofish%27+or+by+hinting+the+type+of+x+to+the+compiler.+You+may+try+both.%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+Major+hint%3A+Have+a+look+at+the+Iter+trait+and+at+the+explanation+of+its+collect+function.+%0A%2F%2F+Especially+the+part+about+Result+is+interesting.%0A) - ["iterators4.rs"](https://play.rust-lang.org/?code=%2F%2F+iterators4.rs%0A%0Apub+fn+factorial%28num%3A+u64%29+-%3E+u64+%7B%0A++++%2F%2F+Complete+this+function+to+return+factorial+of+num%0A++++%2F%2F+Do+not+use%3A%0A++++%2F%2F+-+return%0A++++%2F%2F+For+extra+fun+don%27t+use%3A%0A++++%2F%2F+-+imperative+style+loops+%28for%2C+while%29%0A++++%2F%2F+-+additional+variables%0A++++%2F%2F+For+the+most+fun+don%27t+use%3A%0A++++%2F%2F+-+recursion%0A++++%2F%2F+Scroll+down+for+hints.%0A%7D%0A%0A%23%5Bcfg%28test%29%5D%0Amod+tests+%7B%0A++++use+super%3A%3A*%3B%0A%0A++++%23%5Btest%5D%0A++++fn+factorial_of_1%28%29+%7B%0A++++++++assert_eq%21%281%2C+factorial%281%29%29%3B%0A++++%7D%0A++++%23%5Btest%5D%0A++++fn+factorial_of_2%28%29+%7B%0A++++++++assert_eq%21%282%2C+factorial%282%29%29%3B%0A++++%7D%0A%0A++++%23%5Btest%5D%0A++++fn+factorial_of_4%28%29+%7B%0A++++++++assert_eq%21%2824%2C+factorial%284%29%29%3B%0A++++%7D%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+In+an+imperative+language+you+might+write+a+for+loop+to+iterate+through%0A%2F%2F+multiply+the+values+into+a+mutable+variable.+Or+you+might+write+code+more%0A%2F%2F+functionally+with+recursion+and+a+match+clause.+But+you+can+also+use+ranges%0A%2F%2F+and+iterators+to+solve+this+in+rust.%0A) ### Threads @@ -170,7 +170,7 @@ example](https://doc.rust-lang.org/1.4.0/book/first-edition/dining-philosophers. [Concurrency Chapter](https://doc.rust-lang.org/book/second-edition/ch16-01-threads.html) from the book. -- ["threads1.rs"](https://play.rust-lang.org/?code=%2F%2F+threads1.rs%0A%2F%2F+Make+this+compile%21+Scroll+down+for+hints+%3A%29+The+idea+is+the+thread%0A%2F%2F+spawned+on+line+19+is+completing+jobs+while+the+main+thread+is%0A%2F%2F+monitoring+progress+until+10+jobs+are+completed.+If+you+see+6+lines%0A%2F%2F+of+%22waiting...%22+and+the+program+ends+without+timing+out+the+playground%2C%0A%2F%2F+you%27ve+got+it+%3A%29%0A%0Ause+std%3A%3Async%3A%3AArc%3B%0Ause+std%3A%3Athread%3B%0Ause+std%3A%3Atime%3A%3ADuration%3B%0A%0Astruct+JobStatus+%7B%0A++++jobs_completed%3A+u32%2C%0A%7D%0A%0Afn+main%28%29+%7B%0A++++let+status+%3D+Arc%3A%3Anew%28JobStatus+%7B+jobs_completed%3A+0+%7D%29%3B%0A++++let+status_shared+%3D+status.clone%28%29%3B%0A++++thread%3A%3Aspawn%28move+%7C%7C+%7B%0A++++++++for+_+in+0..10+%7B%0A++++++++++++thread%3A%3Asleep%28Duration%3A%3Afrom_millis%28250%29%29%3B%0A++++++++++++status_shared.jobs_completed+%2B%3D+1%3B%0A++++++++%7D%0A++++%7D%29%3B%0A++++while+status.jobs_completed+%3C+10+%7B%0A++++++++println%21%28%22waiting...+%22%29%3B%0A++++++++thread%3A%3Asleep%28Duration%3A%3Afrom_millis%28500%29%29%3B%0A++++%7D%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+%60Arc%60+is+an+Atomic+Reference+Counted+pointer+that+allows+safe%2C+shared+access%0A%2F%2F+to+**immutable**+data.+But+we+want+to+*change*+the+number+of+%60jobs_completed%60%0A%2F%2F+so+we%27ll+need+to+also+use+another+type+that+will+only+allow+one+thread+to%0A%2F%2F+mutate+the+data+at+a+time.+Take+a+look+at+this+section+of+the+book%3A%0A%2F%2F+https%3A%2F%2Fdoc.rust-lang.org%2Fstable%2Fbook%2Fconcurrency.html%23safe-shared-mutable-state%0A%2F%2F+and+keep+scrolling+if+you%27d+like+more+hints+%3A%29%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+Do+you+now+have+an+%60Arc%60+%60Mutex%60+%60JobStatus%60+at+the+beginning+of+main%3F+Like%3A%0A%2F%2F+%60let+status+%3D+Arc%3A%3Anew%28Mutex%3A%3Anew%28JobStatus+%7B+jobs_completed%3A+0+%7D%29%29%3B%60%0A%2F%2F+Similar+to+the+code+in+the+example+in+the+book+that+happens+after+the+text%0A%2F%2F+that+says+%22We+can+use+Arc%3CT%3E+to+fix+this.%22.+If+not%2C+give+that+a+try%21+If+you%0A%2F%2F+do+and+would+like+more+hints%2C+keep+scrolling%21%21%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+Make+sure+neither+of+your+threads+are+holding+onto+the+lock+of+the+mutex%0A%2F%2F+while+they+are+sleeping%2C+since+this+will+prevent+the+other+thread+from%0A%2F%2F+being+allowed+to+get+the+lock.+Locks+are+automatically+released+when%0A%2F%2F+they+go+out+of+scope.%0A%0A%2F%2F+Ok%2C+so%2C+real+talk%2C+this+was+actually+tricky+for+*me*+to+do+too.+And%0A%2F%2F+I+could+see+a+lot+of+different+problems+you+might+run+into%2C+so+at+this%0A%2F%2F+point+I%27m+not+sure+which+one+you%27ve+hit+%3A%29+Please+see+a+few+possible%0A%2F%2F+answers+on+https%3A%2F%2Fgithub.com%2Fcarols10cents%2Frustlings%2Fissues%2F3+--%0A%2F%2F+mine+is+a+little+more+complicated+because+I+decided+I+wanted+to+see%0A%2F%2F+the+number+of+jobs+currently+done+when+I+was+checking+the+status.%0A%0A%2F%2F+Please+open+an+issue+if+you%27re+still+running+into+a+problem+that%0A%2F%2F+these+hints+are+not+helping+you+with%2C+or+if+you%27ve+looked+at+the+sample%0A%2F%2F+answers+and+don%27t+understand+why+they+work+and+yours+doesn%27t.%0A%0A%2F%2F+If+you%27ve+learned+from+the+sample+solutions%2C+I+encourage+you+to+come%0A%2F%2F+back+to+this+exercise+and+try+it+again+in+a+few+days+to+reinforce%0A%2F%2F+what+you%27ve+learned+%3A%29%0A) +- ["threads1.rs"](https://play.rust-lang.org/?code=%2F%2F+threads1.rs%0A%2F%2F+Make+this+compile%21+Scroll+down+for+hints+%3A%29+The+idea+is+the+thread%0A%2F%2F+spawned+on+line+19+is+completing+jobs+while+the+main+thread+is%0A%2F%2F+monitoring+progress+until+10+jobs+are+completed.+If+you+see+6+lines%0A%2F%2F+of+%22waiting...%22+and+the+program+ends+without+timing+out+the+playground%2C%0A%2F%2F+you%27ve+got+it+%3A%29%0A%0Ause+std%3A%3Async%3A%3AArc%3B%0Ause+std%3A%3Athread%3B%0Ause+std%3A%3Atime%3A%3ADuration%3B%0A%0Astruct+JobStatus+%7B%0A++++jobs_completed%3A+u32%2C%0A%7D%0A%0Afn+main%28%29+%7B%0A++++let+status+%3D+Arc%3A%3Anew%28JobStatus+%7B+jobs_completed%3A+0+%7D%29%3B%0A++++let+status_shared+%3D+status.clone%28%29%3B%0A++++thread%3A%3Aspawn%28move+%7C%7C+%7B%0A++++++++for+_+in+0..10+%7B%0A++++++++++++thread%3A%3Asleep%28Duration%3A%3Afrom_millis%28250%29%29%3B%0A++++++++++++status_shared.jobs_completed+%2B%3D+1%3B%0A++++++++%7D%0A++++%7D%29%3B%0A++++while+status.jobs_completed+%3C+10+%7B%0A++++++++println%21%28%22waiting...+%22%29%3B%0A++++++++thread%3A%3Asleep%28Duration%3A%3Afrom_millis%28500%29%29%3B%0A++++%7D%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+%60Arc%60+is+an+Atomic+Reference+Counted+pointer+that+allows+safe%2C+shared+access%0A%2F%2F+to+**immutable**+data.+But+we+want+to+*change*+the+number+of+%60jobs_completed%60%0A%2F%2F+so+we%27ll+need+to+also+use+another+type+that+will+only+allow+one+thread+to%0A%2F%2F+mutate+the+data+at+a+time.+Take+a+look+at+this+section+of+the+book%3A%0A%2F%2F+https%3A%2F%2Fdoc.rust-lang.org%2Fstable%2Fbook%2Fsecond-edition%2Fch16-03-shared-state.html%23atomic-reference-counting-with-arct%0A%2F%2F+and+keep+scrolling+if+you%27d+like+more+hints+%3A%29%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+Do+you+now+have+an+%60Arc%60+%60Mutex%60+%60JobStatus%60+at+the+beginning+of+main%3F+Like%3A%0A%2F%2F+%60let+status+%3D+Arc%3A%3Anew%28Mutex%3A%3Anew%28JobStatus+%7B+jobs_completed%3A+0+%7D%29%29%3B%60%0A%2F%2F+Similar+to+the+code+in+the+example+in+the+book+that+happens+after+the+text%0A%2F%2F+that+says+%22We+can+use+Arc%3CT%3E+to+fix+this.%22.+If+not%2C+give+that+a+try%21+If+you%0A%2F%2F+do+and+would+like+more+hints%2C+keep+scrolling%21%21%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F+Make+sure+neither+of+your+threads+are+holding+onto+the+lock+of+the+mutex%0A%2F%2F+while+they+are+sleeping%2C+since+this+will+prevent+the+other+thread+from%0A%2F%2F+being+allowed+to+get+the+lock.+Locks+are+automatically+released+when%0A%2F%2F+they+go+out+of+scope.%0A%0A%2F%2F+Ok%2C+so%2C+real+talk%2C+this+was+actually+tricky+for+*me*+to+do+too.+And%0A%2F%2F+I+could+see+a+lot+of+different+problems+you+might+run+into%2C+so+at+this%0A%2F%2F+point+I%27m+not+sure+which+one+you%27ve+hit+%3A%29+Please+see+a+few+possible%0A%2F%2F+answers+on+https%3A%2F%2Fgithub.com%2Fcarols10cents%2Frustlings%2Fissues%2F3+--%0A%2F%2F+mine+is+a+little+more+complicated+because+I+decided+I+wanted+to+see%0A%2F%2F+the+number+of+jobs+currently+done+when+I+was+checking+the+status.%0A%0A%2F%2F+Please+open+an+issue+if+you%27re+still+running+into+a+problem+that%0A%2F%2F+these+hints+are+not+helping+you+with%2C+or+if+you%27ve+looked+at+the+sample%0A%2F%2F+answers+and+don%27t+understand+why+they+work+and+yours+doesn%27t.%0A%0A%2F%2F+If+you%27ve+learned+from+the+sample+solutions%2C+I+encourage+you+to+come%0A%2F%2F+back+to+this+exercise+and+try+it+again+in+a+few+days+to+reinforce%0A%2F%2F+what+you%27ve+learned+%3A%29%0A) ### Uncategorized From 961d7252276f8e1f6ed942e5e7fe4d5a22c55e18 Mon Sep 17 00:00:00 2001 From: Katharina Fey Date: Thu, 16 Aug 2018 16:33:27 -0500 Subject: [PATCH 05/15] Fixing main function errors in move_semantics/ --- Cargo.lock | 133 ++++++++++++++++-------------- move_semantics/move_semantics1.rs | 2 +- move_semantics/move_semantics2.rs | 2 +- move_semantics/move_semantics3.rs | 2 +- move_semantics/move_semantics4.rs | 2 +- 5 files changed, 73 insertions(+), 68 deletions(-) diff --git a/Cargo.lock b/Cargo.lock index 7bff901..c6ef582 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -8,41 +8,44 @@ dependencies = [ [[package]] name = "ansi_term" -version = "0.10.2" +version = "0.11.0" source = "registry+https://github.com/rust-lang/crates.io-index" +dependencies = [ + "winapi 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)", +] [[package]] name = "atty" -version = "0.2.6" +version = "0.2.10" source = "registry+https://github.com/rust-lang/crates.io-index" dependencies = [ - "libc 0.2.37 (registry+https://github.com/rust-lang/crates.io-index)", + "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)", "termion 1.5.1 (registry+https://github.com/rust-lang/crates.io-index)", "winapi 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)", ] [[package]] name = "bitflags" -version = "1.0.1" +version = "1.0.3" source = "registry+https://github.com/rust-lang/crates.io-index" [[package]] name = "cfg-if" -version = "0.1.2" +version = "0.1.3" source = "registry+https://github.com/rust-lang/crates.io-index" [[package]] name = "clap" -version = "2.30.0" +version = "2.31.2" source = "registry+https://github.com/rust-lang/crates.io-index" dependencies = [ - "ansi_term 0.10.2 (registry+https://github.com/rust-lang/crates.io-index)", - "atty 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)", - "bitflags 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)", + "ansi_term 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)", + "atty 0.2.10 (registry+https://github.com/rust-lang/crates.io-index)", + "bitflags 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)", "strsim 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)", "textwrap 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)", - "unicode-width 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)", - "vec_map 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)", + "unicode-width 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)", + "vec_map 0.8.1 (registry+https://github.com/rust-lang/crates.io-index)", ] [[package]] @@ -114,17 +117,17 @@ source = "registry+https://github.com/rust-lang/crates.io-index" [[package]] name = "handlebars" -version = "0.32.0" +version = "0.32.3" source = "registry+https://github.com/rust-lang/crates.io-index" dependencies = [ "lazy_static 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)", "log 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)", "pest 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)", - "pest_derive 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)", + "pest_derive 1.0.7 (registry+https://github.com/rust-lang/crates.io-index)", "quick-error 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)", - "regex 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)", - "serde 1.0.27 (registry+https://github.com/rust-lang/crates.io-index)", - "serde_json 1.0.10 (registry+https://github.com/rust-lang/crates.io-index)", + "regex 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)", + "serde 1.0.59 (registry+https://github.com/rust-lang/crates.io-index)", + "serde_json 1.0.17 (registry+https://github.com/rust-lang/crates.io-index)", ] [[package]] @@ -134,12 +137,12 @@ source = "registry+https://github.com/rust-lang/crates.io-index" dependencies = [ "matches 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)", "unicode-bidi 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)", - "unicode-normalization 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)", + "unicode-normalization 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)", ] [[package]] name = "itoa" -version = "0.3.4" +version = "0.4.1" source = "registry+https://github.com/rust-lang/crates.io-index" [[package]] @@ -149,7 +152,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index" [[package]] name = "libc" -version = "0.2.37" +version = "0.2.41" source = "registry+https://github.com/rust-lang/crates.io-index" [[package]] @@ -157,7 +160,7 @@ name = "log" version = "0.4.1" source = "registry+https://github.com/rust-lang/crates.io-index" dependencies = [ - "cfg-if 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)", + "cfg-if 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)", ] [[package]] @@ -170,14 +173,9 @@ name = "memchr" version = "2.0.1" source = "registry+https://github.com/rust-lang/crates.io-index" dependencies = [ - "libc 0.2.37 (registry+https://github.com/rust-lang/crates.io-index)", + "libc 0.2.41 (registry+https://github.com/rust-lang/crates.io-index)", ] -[[package]] -name = "num-traits" -version = "0.2.1" -source = "registry+https://github.com/rust-lang/crates.io-index" - [[package]] name = "percent-encoding" version = "1.0.1" @@ -190,7 +188,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index" [[package]] name = "pest_derive" -version = "1.0.6" +version = "1.0.7" source = "registry+https://github.com/rust-lang/crates.io-index" dependencies = [ "pest 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)", @@ -203,7 +201,7 @@ name = "prlink" version = "0.1.0" source = "git+https://github.com/btbytes/prlink#f0536ed3b322072d65c42da2fc2a817b77d77308" dependencies = [ - "clap 2.30.0 (registry+https://github.com/rust-lang/crates.io-index)", + "clap 2.31.2 (registry+https://github.com/rust-lang/crates.io-index)", "glob 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)", "url 1.7.0 (registry+https://github.com/rust-lang/crates.io-index)", ] @@ -220,7 +218,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index" [[package]] name = "redox_syscall" -version = "0.1.37" +version = "0.1.38" source = "registry+https://github.com/rust-lang/crates.io-index" [[package]] @@ -228,49 +226,51 @@ name = "redox_termios" version = "0.1.1" source = "registry+https://github.com/rust-lang/crates.io-index" dependencies = [ - "redox_syscall 0.1.37 (registry+https://github.com/rust-lang/crates.io-index)", + "redox_syscall 0.1.38 (registry+https://github.com/rust-lang/crates.io-index)", ] [[package]] name = "regex" -version = "0.2.6" +version = "1.0.0" source = "registry+https://github.com/rust-lang/crates.io-index" dependencies = [ "aho-corasick 0.6.4 (registry+https://github.com/rust-lang/crates.io-index)", "memchr 2.0.1 (registry+https://github.com/rust-lang/crates.io-index)", - "regex-syntax 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)", + "regex-syntax 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)", "thread_local 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)", "utf8-ranges 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)", ] [[package]] name = "regex-syntax" -version = "0.4.2" +version = "0.6.0" source = "registry+https://github.com/rust-lang/crates.io-index" +dependencies = [ + "ucd-util 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)", +] [[package]] name = "rustlings" version = "0.1.0" dependencies = [ - "handlebars 0.32.0 (registry+https://github.com/rust-lang/crates.io-index)", + "handlebars 0.32.3 (registry+https://github.com/rust-lang/crates.io-index)", "prlink 0.1.0 (git+https://github.com/btbytes/prlink)", - "serde_json 1.0.10 (registry+https://github.com/rust-lang/crates.io-index)", + "serde_json 1.0.17 (registry+https://github.com/rust-lang/crates.io-index)", ] [[package]] name = "serde" -version = "1.0.27" +version = "1.0.59" source = "registry+https://github.com/rust-lang/crates.io-index" [[package]] name = "serde_json" -version = "1.0.10" +version = "1.0.17" source = "registry+https://github.com/rust-lang/crates.io-index" dependencies = [ "dtoa 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)", - "itoa 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)", - "num-traits 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)", - "serde 1.0.27 (registry+https://github.com/rust-lang/crates.io-index)", + "itoa 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)", + "serde 1.0.59 (registry+https://github.com/rust-lang/crates.io-index)", ] [[package]] @@ -301,8 +301,8 @@ name = "termion" version = "1.5.1" source = "registry+https://github.com/rust-lang/crates.io-index" dependencies = [ - "libc 0.2.37 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Scroll down for hints :) -pub fn main() { +fn main() { let vec0 = Vec::new(); let vec1 = fill_vec(vec0); diff --git a/move_semantics/move_semantics2.rs b/move_semantics/move_semantics2.rs index bc42d8e..b50e349 100644 --- a/move_semantics/move_semantics2.rs +++ b/move_semantics/move_semantics2.rs @@ -1,7 +1,7 @@ // move_semantics2.rs // Make me compile without changing line 10! Scroll down for hints :) -pub fn main() { +fn main() { let vec0 = Vec::new(); let mut vec1 = fill_vec(vec0); diff --git a/move_semantics/move_semantics3.rs b/move_semantics/move_semantics3.rs index 7805d44..8e7b0ad 100644 --- a/move_semantics/move_semantics3.rs +++ b/move_semantics/move_semantics3.rs @@ -3,7 +3,7 @@ // (no lines with multiple semicolons necessary!) // Scroll down for hints :) -pub fn main() { +fn main() { let vec0 = Vec::new(); let mut vec1 = fill_vec(vec0); diff --git a/move_semantics/move_semantics4.rs b/move_semantics/move_semantics4.rs index 2b1ed8a..903a330 100644 --- a/move_semantics/move_semantics4.rs +++ b/move_semantics/move_semantics4.rs @@ -3,7 +3,7 @@ // in `fn main`, we instead create it within `fn fill_vec` and transfer the // freshly created vector from fill_vec to its caller. 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winapi-i686-pc-windows-gnu 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6" -"checksum winapi-x86_64-pc-windows-gnu 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f" From 3f2d921fef5a6ddbc1131124989998bfe5c19920 Mon Sep 17 00:00:00 2001 From: pawel duzinkiewicz Date: Tue, 9 Oct 2018 20:28:54 +0200 Subject: [PATCH 07/15] fix dead example link --- README-template.hbs | 2 +- README.md | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/README-template.hbs b/README-template.hbs index 5cfec7f..892fd6d 100644 --- a/README-template.hbs +++ b/README-template.hbs @@ -164,7 +164,7 @@ docs](https://doc.rust-lang.org/stable/std/iter/trait.Iterator.html). ### Threads See [the Dining Philosophers -example](https://doc.rust-lang.org/1.4.0/book/first-edition/dining-philosophers.html) and the +example](https://doc.rust-lang.org/1.4.0/book/dining-philosophers.html) and the [Concurrency Chapter](https://doc.rust-lang.org/book/second-edition/ch16-01-threads.html) from the book. diff --git a/README.md b/README.md index 56ae8e8..ac4b4b6 100644 --- a/README.md +++ b/README.md @@ -177,7 +177,7 @@ docs](https://doc.rust-lang.org/stable/std/iter/trait.Iterator.html). ### Threads See [the Dining Philosophers -example](https://doc.rust-lang.org/1.4.0/book/first-edition/dining-philosophers.html) and the +example](https://doc.rust-lang.org/1.4.0/book/dining-philosophers.html) and the [Concurrency Chapter](https://doc.rust-lang.org/book/second-edition/ch16-01-threads.html) from the book. From a6bb340c2cb9a6a79bc5ba3658e4c66dedc4546d Mon Sep 17 00:00:00 2001 From: Michael-Lai fx Date: Thu, 11 Oct 2018 16:56:06 +0800 Subject: [PATCH 08/15] More detail about expression and statement --- functions/functions5.rs | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/functions/functions5.rs b/functions/functions5.rs index f8fac5d..b074d72 100644 --- a/functions/functions5.rs +++ b/functions/functions5.rs @@ -40,5 +40,8 @@ fn square(num: i32) -> i32 { // This is a really common error that can be fixed by removing one character. // It happens because Rust distinguishes between expressions and statements: expressions return -// a value and statements don't. We want to return a value from the `square` function, but it -// isn't returning one right now... +// a value based on its operand and statements simply retun a `()` type which just like `void` in C/C++ language. +// We want to return a value of `i32` type from the `square` function, but it is returning a `()` type... +// They are not the same. There are two solusions: +// 1. Add a `return` ahead of `num * num;` +// 2. remove `;`, make it to be `num * num` From bce303259f45bca1e04c470c8c3959dd59da2e3d Mon Sep 17 00:00:00 2001 From: Michael-Lai fx Date: Thu, 11 Oct 2018 20:02:19 +0800 Subject: [PATCH 09/15] Update functions5.rs --- functions/functions5.rs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/functions/functions5.rs b/functions/functions5.rs index b074d72..a7845e9 100644 --- a/functions/functions5.rs +++ b/functions/functions5.rs @@ -40,7 +40,7 @@ fn square(num: i32) -> i32 { // This is a really common error that can be fixed by removing one character. // It happens because Rust distinguishes between expressions and statements: expressions return -// a value based on its operand and statements simply retun a `()` type which just like `void` in C/C++ language. +// a value based on its operand, and statements simply retun a () type which behaves just like `void` in C/C++ language. // We want to return a value of `i32` type from the `square` function, but it is returning a `()` type... // They are not the same. There are two solusions: // 1. Add a `return` ahead of `num * num;` From 33565401e29c067383450501f4b67217888e6514 Mon Sep 17 00:00:00 2001 From: olivia hugger Date: Thu, 11 Oct 2018 14:03:59 +0200 Subject: [PATCH 10/15] Update functions5.rs --- functions/functions5.rs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/functions/functions5.rs b/functions/functions5.rs index a7845e9..da6b6f9 100644 --- a/functions/functions5.rs +++ b/functions/functions5.rs @@ -40,7 +40,7 @@ fn square(num: i32) -> i32 { // This is a really common error that can be fixed by removing one character. // It happens because Rust distinguishes between expressions and statements: expressions return -// a value based on its operand, and statements simply retun a () type which behaves just like `void` in C/C++ language. +// a value based on its operand, and statements simply return a () type which behaves just like `void` in C/C++ language. // We want to return a value of `i32` type from the `square` function, but it is returning a `()` type... // They are not the same. There are two solusions: // 1. Add a `return` ahead of `num * num;` From 5045db700a8ed30b9b73d36142c87ba5a0327f96 Mon Sep 17 00:00:00 2001 From: Chad Dougherty Date: Fri, 26 Oct 2018 16:22:23 -0400 Subject: [PATCH 11/15] Update functions5.rs simple typo: solusions -> solutions --- functions/functions5.rs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/functions/functions5.rs b/functions/functions5.rs index da6b6f9..d3ff002 100644 --- a/functions/functions5.rs +++ b/functions/functions5.rs @@ -42,6 +42,6 @@ fn square(num: i32) -> i32 { // It happens because Rust distinguishes between expressions and statements: expressions return // a value based on its operand, and statements simply return a () type which behaves just like `void` in C/C++ language. // We want to return a value of `i32` type from the `square` function, but it is returning a `()` type... -// They are not the same. There are two solusions: +// They are not the same. There are two solutions: // 1. Add a `return` ahead of `num * num;` // 2. remove `;`, make it to be `num * num` From a1668451e1e6a81b6cd9569e11ab6f56e3c05e2c Mon Sep 17 00:00:00 2001 From: lukabavdaz Date: Wed, 31 Oct 2018 04:01:42 +0100 Subject: [PATCH 12/15] Add exercise for creating references in patterns --- README-template.hbs | 1 + README.md | 1 + ex6.rs | 47 +++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 49 insertions(+) create mode 100644 ex6.rs diff --git a/README-template.hbs b/README-template.hbs index 892fd6d..32838d5 100644 --- a/README-template.hbs +++ b/README-template.hbs @@ -179,6 +179,7 @@ A few exercises based on things I've encountered or had trouble with getting use {{ playground_link "ex3.rs" }} {{ playground_link "ex4.rs" }} {{ playground_link "ex5.rs" }} +{{ playground_link "ex6.rs" }} ## To help with this repo/TODO list diff --git a/README.md b/README.md index ac4b4b6..cc2cb25 100644 --- a/README.md +++ b/README.md @@ -192,6 +192,7 @@ A few exercises based on things I've encountered or had trouble with getting use - ["ex3.rs"](https://play.rust-lang.org/?code=%2F%2F+ex3.rs%0A%2F%2F+Make+me+compile%21%0A%0Astruct+Foo+%7B%0A++++capacity%3A+i32%2C%0A%7D%0A%0Afn+main%28%29+%7B%0A++++println%21%28%22%7B%3A%3F%7D%22%2C+Foo+%7B+capacity%3A+3+%7D%29%3B%0A%7D%0A) - ["ex4.rs"](https://play.rust-lang.org/?code=%2F%2F+ex4.rs%0A%2F%2F+Make+me+compile%21%0A%0Afn+something%28%29+-%3E+Result%3Ci32%2C+std%3A%3Anum%3A%3AParseIntError%3E+%7B%0A++++let+x%3Ai32+%3D+%223%22.parse%28%29%3B%0A++++Ok%28x+*+4%29%0A%7D%0A%0Afn+main%28%29+%7B%0A++++match+something%28%29+%7B%0A++++++++Ok%28..%29+%3D%3E+println%21%28%22You+win%21%22%29%2C%0A++++++++Err%28e%29+%3D%3E+println%21%28%22Oh+no+something+went+wrong%3A+%7B%7D%22%2C+e%29%2C%0A++++%7D%0A%7D%0A) - ["ex5.rs"](https://play.rust-lang.org/?code=%2F%2F+ex5.rs%0A%2F%2F+Make+me+compile%21%0A%0Aenum+Reaction%3C%27a%3E+%7B%0A++++Sad%28%26%27a+str%29%2C%0A++++Happy%28%26%27a+str%29%2C%0A%7D%0A%0Afn+express%28sentiment%3A+Reaction%29+%7B%0A++++match+sentiment+%7B%0A++++++++Reaction%3A%3ASad%28s%29+%3D%3E+println%21%28%22%3A%28+%7B%7D%22%2C+s%29%2C%0A++++++++Reaction%3A%3AHappy%28s%29+%3D%3E+println%21%28%22%3A%29+%7B%7D%22%2C+s%29%2C%0A++++%7D%0A%7D%0A%0Afn+main+%28%29+%7B%0A++++let+x+%3D+Reaction%3A%3AHappy%28%22It%27s+a+great+day+for+Rust%21%22%29%3B%0A++++express%28x%29%3B%0A++++express%28x%29%3B%0A++++let+y+%3D+Reaction%3A%3ASad%28%22This+code+doesn%27t+compile+yet.%22%29%3B%0A++++express%28y%29%3B%0A%7D%0A) +- ["ex6.rs"](https://play.rust-lang.org/?code=%2F%2F%20ex6.rs%0A%2F%2F%20Make%20me%20compile!%20Scroll%20down%20for%20hints%20%3A)%0A%0Afn%20main()%20%7B%0A%20%20%20%20let%20robot_name%20%3D%20Some(String%3A%3Afrom(%22Bors%22))%3B%0A%20%20%20%20%0A%20%20%20%20match%20robot_name%20%7B%0A%20%20%20%20%20%20%20%20Some(name)%20%3D%3E%20println!(%22Found%20a%20name%3A%20%7B%7D%22%2C%20name)%2C%0A%20%20%20%20%20%20%20%20None%20%3D%3E%20()%2C%0A%20%20%20%20%7D%0A%20%20%20%20%0A%20%20%20%20println!(%22robot_name%20is%3A%20%7B%3A%3F%7D%22%2C%20robot_name)%3B%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F%20Hint%3A%20The%20following%20two%20statements%20are%20equivalent%3A%0A%2F%2F%20let%20x%20%3D%20%26y%3B%0A%2F%2F%20let%20ref%20x%20%3D%20y%3B) ## To help with this repo/TODO list diff --git a/ex6.rs b/ex6.rs new file mode 100644 index 0000000..33e589d --- /dev/null +++ b/ex6.rs @@ -0,0 +1,47 @@ +// ex6.rs +// Make me compile! Scroll down for hints :) + +fn main() { + let robot_name = Some(String::from("Bors")); + + match robot_name { + Some(name) => println!("Found a name: {}", name), + None => (), + } + + println!("robot_name is: {:?}", robot_name); +} + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +// Hint: The following two statements are equivalent: +// let x = &y; +// let ref x = y; From 1de73921662c7f2ccd040b53e84f98ca86fb2656 Mon Sep 17 00:00:00 2001 From: lukabavdaz Date: Wed, 31 Oct 2018 21:49:25 +0100 Subject: [PATCH 13/15] Fix readme The link for ex6,rs should now work properly. --- README.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/README.md b/README.md index cc2cb25..3d5c742 100644 --- a/README.md +++ b/README.md @@ -192,7 +192,7 @@ A few exercises based on things I've encountered or had trouble with getting use - ["ex3.rs"](https://play.rust-lang.org/?code=%2F%2F+ex3.rs%0A%2F%2F+Make+me+compile%21%0A%0Astruct+Foo+%7B%0A++++capacity%3A+i32%2C%0A%7D%0A%0Afn+main%28%29+%7B%0A++++println%21%28%22%7B%3A%3F%7D%22%2C+Foo+%7B+capacity%3A+3+%7D%29%3B%0A%7D%0A) - ["ex4.rs"](https://play.rust-lang.org/?code=%2F%2F+ex4.rs%0A%2F%2F+Make+me+compile%21%0A%0Afn+something%28%29+-%3E+Result%3Ci32%2C+std%3A%3Anum%3A%3AParseIntError%3E+%7B%0A++++let+x%3Ai32+%3D+%223%22.parse%28%29%3B%0A++++Ok%28x+*+4%29%0A%7D%0A%0Afn+main%28%29+%7B%0A++++match+something%28%29+%7B%0A++++++++Ok%28..%29+%3D%3E+println%21%28%22You+win%21%22%29%2C%0A++++++++Err%28e%29+%3D%3E+println%21%28%22Oh+no+something+went+wrong%3A+%7B%7D%22%2C+e%29%2C%0A++++%7D%0A%7D%0A) - ["ex5.rs"](https://play.rust-lang.org/?code=%2F%2F+ex5.rs%0A%2F%2F+Make+me+compile%21%0A%0Aenum+Reaction%3C%27a%3E+%7B%0A++++Sad%28%26%27a+str%29%2C%0A++++Happy%28%26%27a+str%29%2C%0A%7D%0A%0Afn+express%28sentiment%3A+Reaction%29+%7B%0A++++match+sentiment+%7B%0A++++++++Reaction%3A%3ASad%28s%29+%3D%3E+println%21%28%22%3A%28+%7B%7D%22%2C+s%29%2C%0A++++++++Reaction%3A%3AHappy%28s%29+%3D%3E+println%21%28%22%3A%29+%7B%7D%22%2C+s%29%2C%0A++++%7D%0A%7D%0A%0Afn+main+%28%29+%7B%0A++++let+x+%3D+Reaction%3A%3AHappy%28%22It%27s+a+great+day+for+Rust%21%22%29%3B%0A++++express%28x%29%3B%0A++++express%28x%29%3B%0A++++let+y+%3D+Reaction%3A%3ASad%28%22This+code+doesn%27t+compile+yet.%22%29%3B%0A++++express%28y%29%3B%0A%7D%0A) -- ["ex6.rs"](https://play.rust-lang.org/?code=%2F%2F%20ex6.rs%0A%2F%2F%20Make%20me%20compile!%20Scroll%20down%20for%20hints%20%3A)%0A%0Afn%20main()%20%7B%0A%20%20%20%20let%20robot_name%20%3D%20Some(String%3A%3Afrom(%22Bors%22))%3B%0A%20%20%20%20%0A%20%20%20%20match%20robot_name%20%7B%0A%20%20%20%20%20%20%20%20Some(name)%20%3D%3E%20println!(%22Found%20a%20name%3A%20%7B%7D%22%2C%20name)%2C%0A%20%20%20%20%20%20%20%20None%20%3D%3E%20()%2C%0A%20%20%20%20%7D%0A%20%20%20%20%0A%20%20%20%20println!(%22robot_name%20is%3A%20%7B%3A%3F%7D%22%2C%20robot_name)%3B%0A%7D%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%0A%2F%2F%20Hint%3A%20The%20following%20two%20statements%20are%20equivalent%3A%0A%2F%2F%20let%20x%20%3D%20%26y%3B%0A%2F%2F%20let%20ref%20x%20%3D%20y%3B) +- ["ex6.rs"](https://play.rust-lang.org/?code=%2F%2F+ex6.rs%0D%0A%2F%2F+Make+me+compile%21+Scroll+down+for+hints+%3A%29%0D%0A%0D%0Afn+main%28%29+%7B%0D%0A++++let+robot_name+%3D+Some%28String%3A%3Afrom%28%22Bors%22%29%29%3B%0D%0A%0D%0A++++match+robot_name+%7B%0D%0A++++++++Some%28name%29+%3D%3E+println%21%28%22Found+a+name%3A+%7B%7D%22%2C+name%29%2C%0D%0A++++++++None+%3D%3E+%28%29%2C%0D%0A++++%7D%0D%0A%0D%0A++++println%21%28%22robot_name+is%3A+%7B%3A%3F%7D%22%2C+robot_name%29%3B%0D%0A%7D%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%0D%0A%2F%2F+Hint%3A+The+following+two+statements+are+equivalent%3A%0D%0A%2F%2F+let+x+%3D+%26y%3B%0D%0A%2F%2F+let+ref+x+%3D+y%3B%0D%0A) ## To help with this repo/TODO list From ed32b8af55a6adb06cef9d10fbd8391eed3dc7a5 Mon Sep 17 00:00:00 2001 From: olivia hugger Date: Fri, 9 Nov 2018 19:12:57 +0100 Subject: [PATCH 14/15] fix readme typo --- README.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/README.md b/README.md index ac4b4b6..9c06f76 100644 --- a/README.md +++ b/README.md @@ -24,7 +24,7 @@ in the playground to find comments that have hints. * clone the repo to your local environment: `git clone git@github.com:rustlings/rustlings.git` * edit the rustling that you want, per example `variables/variables1.rs` * run `cargo run` in the project folder -* you will notice that you README file was modified and now it has the new content of the file that you edited +* you will notice that your README file was modified and now it has the new content of the file that you edited * click in the new URL in the README and you will redirect to the rust playground and the whole file content it will be loaded * to execute in the rust playground, just click on `run` From 6d512654844539be66bee32e87a4057fab17861b Mon Sep 17 00:00:00 2001 From: olivia Date: Mon, 26 Nov 2018 09:25:57 +0100 Subject: [PATCH 15/15] fix clone instruction to point to https endpoint --- README.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/README.md b/README.md index 9c06f76..2fc6970 100644 --- a/README.md +++ b/README.md @@ -21,7 +21,7 @@ in the playground to find comments that have hints. ### To do these exercises in your local environment and execute them online afterwards: -* clone the repo to your local environment: `git clone git@github.com:rustlings/rustlings.git` +* clone the repo to your local environment: `git clone https://github.com/rustlings/rustlings.git` * edit the rustling that you want, per example `variables/variables1.rs` * run `cargo run` in the project folder * you will notice that your README file was modified and now it has the new content of the file that you edited