Reuse trait implementation of other type

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1

Say I have a struct TheirStruct (maybe in an external crate) that implements the traits Foo and Bar.

I want to create a struct MyStruct that uses the implementation for Foo from TheirStruct and has its own implementation for Bar. Or in other words I want MyStruct to be like a type alias of TheirStruct. I just want to override the Bar trait implementation of TheirStruct.

Any way to do this?

2

There's no builtin automatic way to forward trait implementations. There are crates that might hide some of the boilerplate.
You can implement it yourself.
Make MyStruct a wrapper around TheirStruct:

struct MyStruct(TheirStruct);

Then implement Foo on it and forward to the TheirStruct member and implement Bar they way you want it.

I guess you could also implement Deref<Target=TheirStruct> for MyStruct and thus benefit from auto-dereferencing in some cases.

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