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// 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
#[derive(Debug)]
struct Person {
name: String,
age: usize,
}
// 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 {
name: String::from("John"),
age: 30,
}
}
}
// I AM NOT DONE
// Your task is to complete this implementation
// in order for the line `let p = 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.
//
// 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. 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 onject with the results
impl From<&str> for Person {
fn from(s: &str) -> Person {
}
}
fn main() {
// Use the `from` function
let p1 = Person::from("Mark,20");
// Since From is implemented for Person, we should be able to use Into
let p2: Person = "Gerald,70".into();
println!("{:?}", p1);
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);
}
}
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