How can I enforce equality of two associated type parameters of traits?

Question

I have a function f which takes two arguments of the same type, and a function g which takes two arguments of different types, but both types have to store the same value, so that g can call f with the values contained in the arguments to f. I currently implemented something like this:

fn f<T>(a: T, b: T) {} trait A { type A; fn getter(&self) -> Self::A; } fn g<T: A, U: A>(a: T, b: U) { f(a.getter(), b.getter()) }

What do I have to add to the definition of g to make it work?

See also: stackoverflow.com/q/29345708/155423; stackoverflow.com/q/27893501/155423. — Shepmaster
– Shepmaster, Commented Feb 21, 2017 at 21:55

Shepmaster · Accepted Answer · 2019-03-13 13:59:46Z

4

A where clause works fine:

fn g<T, U>(a: T, b: U) where T: A, U: A<A = T::A>, // where T::A is equal to B::A { f(a.getter(), b.getter()) }

edited Mar 13, 2019 at 13:59

answered Feb 21, 2017 at 21:51

Shepmaster

439k116 gold badges1.3k silver badges1.5k bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Shepmaster · Accepted Answer · 2017-02-21 21:48:35Z

I found a solution. It's not done by a where clause, but this way:

fn g<T: A, U: A<A = T::A>>(a: T, b: U) { // where T::A is equal to B::A f(a.getter(), b.getter()) }

Collectives™ on Stack Overflow

How can I enforce equality of two associated type parameters of traits?

2 Answers 2

Comments

Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Linked

Related