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-rw-r--r--exercises/23_conversions/from_into.rs62
1 files changed, 30 insertions, 32 deletions
diff --git a/exercises/23_conversions/from_into.rs b/exercises/23_conversions/from_into.rs
index 14a62ba..bc2783a 100644
--- a/exercises/23_conversions/from_into.rs
+++ b/exercises/23_conversions/from_into.rs
@@ -1,81 +1,79 @@
-// The From trait is used for value-to-value conversions. If From is implemented
-// correctly for a type, the Into trait should work conversely. You can read
-// more about it at https://doc.rust-lang.org/std/convert/trait.From.html
+// The `From` trait is used for value-to-value conversions. If `From` is
+// implemented, an implementation of `Into` is automatically provided.
+// You can read more about it in the documentation:
+// https://doc.rust-lang.org/std/convert/trait.From.html
#[derive(Debug)]
struct Person {
name: String,
- age: usize,
+ age: u8,
}
-// We implement the Default trait to use it as a fallback
-// when the provided string is not convertible into a Person object
+// We implement the Default trait to use it as a fallback when the provided
+// string is not convertible into a `Person` object.
impl Default for Person {
- fn default() -> Person {
- Person {
+ fn default() -> Self {
+ Self {
name: String::from("John"),
age: 30,
}
}
}
-// Your task is to complete this implementation in order for the line `let p1 =
-// Person::from("Mark,20")` to compile. Please note that you'll need to parse the
-// age component into a `usize` with something like `"4".parse::<usize>()`. The
-// outcome of this needs to be handled appropriately.
+// TODO: Complete this `From` implementation to be able to parse a `Person`
+// out of a string in the form of "Mark,20".
+// Note that you'll need to parse the age component into a `u8` with something
+// like `"4".parse::<u8>()`.
//
// Steps:
-// 1. If the length of the provided string is 0, then return the default of
-// Person.
-// 2. Split the given string on the commas present in it.
-// 3. Extract the first element from the split operation and use it as the name.
-// 4. If the name is empty, then return the default of Person.
-// 5. Extract the other element from the split operation and parse it into a
-// `usize` as the age.
-// If while parsing the age, something goes wrong, then return the default of
-// Person. Otherwise, then return an instantiated Person object with the results
-
+// 1. Split the given string on the commas present in it.
+// 2. If the split operation returns less or more than 2 elements, return the
+// default of `Person`.
+// 3. Use the first element from the split operation as the name.
+// 4. If the name is empty, return the default of `Person`.
+// 5. Parse the second element from the split operation into a `u8` as the age.
+// 6. If parsing the age fails, return the default of `Person`.
impl From<&str> for Person {
- fn from(s: &str) -> Person {}
+ fn from(s: &str) -> Self {}
}
fn main() {
- // Use the `from` function
+ // Use the `from` function.
let p1 = Person::from("Mark,20");
- // Since From is implemented for Person, we should be able to use Into
+ println!("{p1:?}");
+
+ // Since `From` is implemented for Person, we are able to use `Into`.
let p2: Person = "Gerald,70".into();
- println!("{:?}", p1);
- println!("{:?}", p2);
+ println!("{p2:?}");
}
#[cfg(test)]
mod tests {
use super::*;
+
#[test]
fn test_default() {
- // Test that the default person is 30 year old John
let dp = Person::default();
assert_eq!(dp.name, "John");
assert_eq!(dp.age, 30);
}
+
#[test]
fn test_bad_convert() {
- // Test that John is returned when bad string is provided
let p = Person::from("");
assert_eq!(p.name, "John");
assert_eq!(p.age, 30);
}
+
#[test]
fn test_good_convert() {
- // Test that "Mark,20" works
let p = Person::from("Mark,20");
assert_eq!(p.name, "Mark");
assert_eq!(p.age, 20);
}
+
#[test]
fn test_bad_age() {
- // Test that "Mark,twenty" will return the default person due to an
- // error in parsing age
let p = Person::from("Mark,twenty");
assert_eq!(p.name, "John");
assert_eq!(p.age, 30);