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37 lines
787 B
Markdown
37 lines
787 B
Markdown
# Trait Bounds
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When working with generics, you often want to limit the types. You can do this
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with `T: Trait` or `impl Trait`:
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```rust,editable
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fn duplicate<T: Clone>(a: T) -> (T, T) {
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(a.clone(), a.clone())
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}
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// struct NotClonable;
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fn main() {
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let foo = String::from("foo");
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let pair = duplicate(foo);
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}
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```
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<details>
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Consider showing a `where` clause syntax. Students can encounter it too when reading code.
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```rust,ignore
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fn duplicate<T>(a: T) -> (T, T)
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where
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T: Clone,
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{
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(a.clone(), a.clone())
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}
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```
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* It declutters the function signature if you have many parameters.
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* It has additional features making it more powerful.
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* If someone asks, the extra feature is that the type on the left of ":" can be arbitrary, like `Option<T>`.
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</details>
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