157 lines
2.8 KiB
Markdown
157 lines
2.8 KiB
Markdown
# Generics
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### Functions
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1. πππ
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```rust,editable
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// Fill in the blanks to make it work
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struct A; // Concrete type `A`.
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struct S(A); // Concrete type `S`.
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struct SGen<T>(T); // Generic type `SGen`.
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fn reg_fn(_s: S) {}
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fn gen_spec_t(_s: SGen<A>) {}
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fn gen_spec_i32(_s: SGen<i32>) {}
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fn generic<T>(_s: SGen<T>) {}
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fn main() {
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// Using the non-generic functions
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reg_fn(__); // Concrete type.
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gen_spec_t(__); // Implicitly specified type parameter `A`.
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gen_spec_i32(__); // Implicitly specified type parameter `i32`.
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// Explicitly specified type parameter `char` to `generic()`.
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generic::<char>(__);
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// Implicitly specified type parameter `char` to `generic()`.
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generic(__);
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println!("Success!");
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}
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```
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2. ππ A function call with explicitly specified type parameters looks like: `fun::<A, B, ...>()`.
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```rust,editable
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// Implement the generic function below.
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fn sum
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fn main() {
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assert_eq!(5, sum(2i8, 3i8));
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assert_eq!(50, sum(20, 30));
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assert_eq!(2.46, sum(1.23, 1.23));
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println!("Success!");
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}
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```
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### Struct and `impl`
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3. π
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```rust,editable
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// Implement struct Point to make it work.
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fn main() {
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let integer = Point { x: 5, y: 10 };
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let float = Point { x: 1.0, y: 4.0 };
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println!("Success!");
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}
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```
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4. ππ
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```rust,editable
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// Modify this struct to make the code work
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struct Point<T> {
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x: T,
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y: T,
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}
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fn main() {
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// DON'T modify this code.
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let p = Point{x: 5, y : "hello".to_string()};
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println!("Success!");
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}
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```
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5. ππ
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```rust,editable
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// Add generic for Val to make the code work, DON'T modify the code in `main`.
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struct Val {
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val: f64,
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}
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impl Val {
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fn value(&self) -> &f64 {
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&self.val
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}
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}
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fn main() {
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let x = Val{ val: 3.0 };
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let y = Val{ val: "hello".to_string()};
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println!("{}, {}", x.value(), y.value());
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}
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```
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### Method
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6. πππ
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```rust,editable
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struct Point<T, U> {
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x: T,
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y: U,
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}
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impl<T, U> Point<T, U> {
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// Implement mixup to make it work, DON'T modify other code.
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fn mixup
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}
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fn main() {
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let p1 = Point { x: 5, y: 10 };
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let p2 = Point { x: "Hello", y: 'δΈ'};
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let p3 = p1.mixup(p2);
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assert_eq!(p3.x, 5);
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assert_eq!(p3.y, 'δΈ');
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println!("Success!");
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}
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```
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7. ππ
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```rust,editable
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// Fix the errors to make the code work.
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struct Point<T> {
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x: T,
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y: T,
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}
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impl Point<f32> {
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fn distance_from_origin(&self) -> f32 {
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(self.x.powi(2) + self.y.powi(2)).sqrt()
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}
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}
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fn main() {
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let p = Point{x: 5, y: 10};
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println!("{}",p.distance_from_origin());
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}
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```
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> You can find the solutions [here](https://github.com/sunface/rust-by-practice/blob/master/solutions/generics-traits/generics.md)(under the solutions path), but only use it when you need it
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