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13.2 Implementation

Similar to functions, implementations require care to remain generic.

struct S; // Concrete type `S`
struct GenericVal<T>(T,); // Generic type `GenericVal`

// impl of GenericVal where we explicitly specify type parameters:
impl GenericVal<f32> {} // Specify `f32`
impl GenericVal<S> {} // Specify `S` as defined above

// `<T>` Must precede the type to remain generic
impl <T> GenericVal<T> {}
struct Val (f64,); struct GenVal<T>(T,); // impl of Val impl Val { fn value(&self) -> &f64 { &self.0 } } // impl of GenVal for a generic type `T` impl <T> GenVal<T> { fn value(&self) -> &T { &self.0 } } fn main() { let x = Val(3.0); let y = GenVal(3i32); println!("{}, {}", x.value(), y.value()); }

See also:

functions returning references, impl, and struct