Trait into_ext::TypeIsEqual[−][src]

pub trait TypeIsEqual {
    type To: ?Sized;
}
Expand description

Helper trait for type equality, necessary to make IntoExt::into_ work.

Generically implemented so that T: TypeIsEqual<To = T> holds for all types.

Example

If you have an S: TypeIsEqual<To = T> bound, this trait can be used by using a generic function with arguments or return values of type S and <S as TypeIsEqual>::To.

fn convert_one_way<S, T>(s: S) -> T
where
    S: TypeIsEqual<To = T>,
{
    fn helper<S>(s: S) -> <S as TypeIsEqual>::To {
        s
    }
    helper(s)
}

fn convert_other_way<S, T>(t: T) -> S
where
    S: TypeIsEqual<To = T>,
{
    fn helper<S>(t: <S as TypeIsEqual>::To) -> S {
        t
    }
    helper(t)
}

The same works if the corresponding types are part of a larger type, e.g. you can convert &mut [Option<S>] to &mut [Option<T>] and things like that.

Associated Types

Two types being equal – e.g. S == T – is written as S: TypeIsEqual<To = T> with this trait.

Implementors