Trait type_equalities::Consumer[−][src]

pub trait Consumer<T: ?Sized, U: ?Sized> {
    type Result;
    fn consume_eq(self) -> Self::Result
    where
        T: IsEqual<U>;
}

A consumer recives evidence of a type equality T == U and computes a result.

Associated Types

type Result[src]

The result type returned from Consumer::consume_eq.

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Required methods

fn consume_eq(self) -> Self::Result where
    T: IsEqual<U>, [src]

The strange where clause enables the consumer to observe that:

  • T == <T as AssocSelf>::Alias by the implementation of AssocSelf
  • T::Alias == U

Directly writing T = U is currently not possible, as tracked by issue #20041.

A workaround, to make it easier for implementors to construct your own Consumer is, if your consumer takes a generic parameter T, store of values with type <T as AliasSelf>::Alias internally. In consume_eq, the compiler will correctly reduce this to U, since it sees the where clause. Additionally, during construction (somewhere else), the compiler sees the impl<T> for AssocSelf, correctly using the first equality. Thus, you don’t have to coerce consumers.

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Implementors

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