70 lines
No EOL
2.3 KiB
Rust
70 lines
No EOL
2.3 KiB
Rust
// TryFrom is a simple and safe type conversion that may fail in a controlled way under some circumstances.
|
|
// Basically, this is the same as From. The main difference is that this should return a Result type
|
|
// instead of the target type itself.
|
|
// You can read more about it at https://doc.rust-lang.org/std/convert/trait.TryFrom.html
|
|
use std::convert::{TryInto, TryFrom};
|
|
|
|
#[derive(Debug)]
|
|
struct Person {
|
|
name: String,
|
|
age: usize,
|
|
}
|
|
|
|
// Your task is to complete this implementation
|
|
// in order for the line `let p = Person::try_from("Mark,20")` to compile
|
|
// and return an Ok result of inner type Person.
|
|
// 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 an error
|
|
// 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 an error
|
|
// Otherwise, then return a Result of a Person object
|
|
impl TryFrom<&str> for Person {
|
|
type Error = String;
|
|
fn try_from(s: &str) -> Result<Self, Self::Error> {
|
|
}
|
|
}
|
|
|
|
fn main() {
|
|
// Use the `from` function
|
|
let p1 = Person::try_from("Mark,20");
|
|
// Since From is implemented for Person, we should be able to use Into
|
|
let p2: Result<Person, _> = "Gerald,70".try_into();
|
|
println!("{:?}", p1);
|
|
println!("{:?}", p2);
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod tests {
|
|
use super::*;
|
|
#[test]
|
|
fn test_bad_convert() {
|
|
// Test that John is returned when bad string is provided
|
|
let p = Person::try_from("");
|
|
assert!(p.is_err());
|
|
}
|
|
#[test]
|
|
fn test_good_convert() {
|
|
// Test that "Mark,20" works
|
|
let p = Person::try_from("Mark,20");
|
|
assert!(p.is_ok());
|
|
let p = p.unwrap();
|
|
assert_eq!(p.name, "Mark");
|
|
assert_eq!(p.age, 20);
|
|
}
|
|
#[test]
|
|
#[should_panic]
|
|
fn test_panic_empty_input() {
|
|
let p: Person = "".try_into().unwrap();
|
|
}
|
|
#[test]
|
|
#[should_panic]
|
|
fn test_panic_bad_age() {
|
|
let p = Person::try_from("Mark,twenty").unwrap();
|
|
}
|
|
} |