Merge pull request #693 from tlyu/trait-obj-tryfrom

fix: use trait objects for try_from_into and from_str
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Abdou Seck 2021-04-05 07:26:19 -04:00 committed by GitHub
commit 995c6f0fb1
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3 changed files with 25 additions and 20 deletions

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@ -2,6 +2,7 @@
// Additionally, upon implementing FromStr, you can use the `parse` method // Additionally, upon implementing FromStr, you can use the `parse` method
// on strings to generate an object of the implementor type. // on strings to generate an object of the implementor type.
// You can read more about it at https://doc.rust-lang.org/std/str/trait.FromStr.html // You can read more about it at https://doc.rust-lang.org/std/str/trait.FromStr.html
use std::error;
use std::str::FromStr; use std::str::FromStr;
#[derive(Debug)] #[derive(Debug)]
@ -23,7 +24,7 @@ struct Person {
// If everything goes well, then return a Result of a Person object // If everything goes well, then return a Result of a Person object
impl FromStr for Person { impl FromStr for Person {
type Err = String; type Err = Box<dyn error::Error>;
fn from_str(s: &str) -> Result<Person, Self::Err> { fn from_str(s: &str) -> Result<Person, Self::Err> {
} }
} }

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@ -3,6 +3,7 @@
// instead of the target type itself. // instead of the target type itself.
// You can read more about it at https://doc.rust-lang.org/std/convert/trait.TryFrom.html // You can read more about it at https://doc.rust-lang.org/std/convert/trait.TryFrom.html
use std::convert::{TryFrom, TryInto}; use std::convert::{TryFrom, TryInto};
use std::error;
#[derive(Debug, PartialEq)] #[derive(Debug, PartialEq)]
struct Color { struct Color {
@ -24,19 +25,19 @@ struct Color {
// Tuple implementation // Tuple implementation
impl TryFrom<(i16, i16, i16)> for Color { impl TryFrom<(i16, i16, i16)> for Color {
type Error = String; type Error = Box<dyn error::Error>;
fn try_from(tuple: (i16, i16, i16)) -> Result<Self, Self::Error> {} fn try_from(tuple: (i16, i16, i16)) -> Result<Self, Self::Error> {}
} }
// Array implementation // Array implementation
impl TryFrom<[i16; 3]> for Color { impl TryFrom<[i16; 3]> for Color {
type Error = String; type Error = Box<dyn error::Error>;
fn try_from(arr: [i16; 3]) -> Result<Self, Self::Error> {} fn try_from(arr: [i16; 3]) -> Result<Self, Self::Error> {}
} }
// Slice implementation // Slice implementation
impl TryFrom<&[i16]> for Color { impl TryFrom<&[i16]> for Color {
type Error = String; type Error = Box<dyn error::Error>;
fn try_from(slice: &[i16]) -> Result<Self, Self::Error> {} fn try_from(slice: &[i16]) -> Result<Self, Self::Error> {}
} }
@ -76,41 +77,43 @@ mod tests {
} }
#[test] #[test]
fn test_tuple_correct() { fn test_tuple_correct() {
let c: Result<Color, String> = (183, 65, 14).try_into(); let c: Result<Color, _> = (183, 65, 14).try_into();
assert!(c.is_ok());
assert_eq!( assert_eq!(
c, c.unwrap(),
Ok(Color { Color {
red: 183, red: 183,
green: 65, green: 65,
blue: 14 blue: 14
}) }
); );
} }
#[test] #[test]
fn test_array_out_of_range_positive() { fn test_array_out_of_range_positive() {
let c: Result<Color, String> = [1000, 10000, 256].try_into(); let c: Result<Color, _> = [1000, 10000, 256].try_into();
assert!(c.is_err()); assert!(c.is_err());
} }
#[test] #[test]
fn test_array_out_of_range_negative() { fn test_array_out_of_range_negative() {
let c: Result<Color, String> = [-10, -256, -1].try_into(); let c: Result<Color, _> = [-10, -256, -1].try_into();
assert!(c.is_err()); assert!(c.is_err());
} }
#[test] #[test]
fn test_array_sum() { fn test_array_sum() {
let c: Result<Color, String> = [-1, 255, 255].try_into(); let c: Result<Color, _> = [-1, 255, 255].try_into();
assert!(c.is_err()); assert!(c.is_err());
} }
#[test] #[test]
fn test_array_correct() { fn test_array_correct() {
let c: Result<Color, String> = [183, 65, 14].try_into(); let c: Result<Color, _> = [183, 65, 14].try_into();
assert!(c.is_ok());
assert_eq!( assert_eq!(
c, c.unwrap(),
Ok(Color { Color {
red: 183, red: 183,
green: 65, green: 65,
blue: 14 blue: 14
}) }
); );
} }
#[test] #[test]
@ -131,14 +134,15 @@ mod tests {
#[test] #[test]
fn test_slice_correct() { fn test_slice_correct() {
let v = vec![183, 65, 14]; let v = vec![183, 65, 14];
let c: Result<Color, String> = Color::try_from(&v[..]); let c: Result<Color, _> = Color::try_from(&v[..]);
assert!(c.is_ok());
assert_eq!( assert_eq!(
c, c.unwrap(),
Ok(Color { Color {
red: 183, red: 183,
green: 65, green: 65,
blue: 14 blue: 14
}) }
); );
} }
#[test] #[test]

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@ -884,5 +884,5 @@ path = "exercises/conversions/from_str.rs"
mode = "test" mode = "test"
hint = """ hint = """
The implementation of FromStr should return an Ok with a Person object, The implementation of FromStr should return an Ok with a Person object,
or an Err with a string if the string is not valid. or an Err with an error if the string is not valid.
This is almost like the `try_from_into` exercise.""" This is almost like the `try_from_into` exercise."""