2dc93cadda
Remove the use of trait objects as errors from `from_str` and `try_from_into`; they seem to have caused a lot of confusion in practice. (Also, it's considered best practice to use custom error types instead of boxed errors in library code.) Instead, use custom error enums, and update hints accordingly. Hints also provide some guidance about converting errors, which could be covered more completely in a future advanced errors section. Also move from_str to directly after the similar exercise `from_into`, for the sake of familiarity when solving. |
||
|---|---|---|
| .. | ||
| README.md | ||
| as_ref_mut.rs | ||
| from_into.rs | ||
| from_str.rs | ||
| try_from_into.rs | ||
| using_as.rs | ||
README.md
Type conversions
Rust offers a multitude of ways to convert a value of a given type into another type.
The simplest form of type conversion is a type cast expression. It is denoted with the binary operator as. For instance, println!("{}", 1 + 1.0); would not compile, since 1 is an integer while 1.0 is a float. However, println!("{}", 1 as f32 + 1.0) should compile. The exercise using_as tries to cover this.
Rust also offers traits that facilitate type conversions upon implementation. These traits can be found under the convert module.
The traits are the following:
FromandIntocovered infrom_intoTryFromandTryIntocovered intry_from_intoAsRefandAsMutcovered inas_ref_mut
Furthermore, the std::str module offers a trait called FromStr which helps with converting strings into target types via the parse method on strings. If properly implemented for a given type Person, then let p: Person = "Mark,20".parse().unwrap() should both compile and run without panicking.
These should be the main ways within the standard library to convert data into your desired types.
Further information
These are not directly covered in the book, but the standard library has a great documentation for it.