Re: interface function member declarations needing parameter attributes ?

[someone via Digitalmars-d-learn]

On Saturday, 17 July 2021 at 22:48:00 UTC, Adam D Ruppe wrote:

On Saturday, 17 July 2021 at 22:43:15 UTC, someone wrote:

So the lesson learned is that interfaces can also mandate member function's parameter attributes then ... right ?

A subclass must accept anything the parent class can, but it can also make it stricter if you want.

class Base {
        void foo(Object o) {}
}

class Derived : Base {
        override void foo(const Object o) {}
}

That's legal because const also accepts mutable. Derived is stricter than Base which is permitted. But the other way around:

class Base {
        void foo(const Object o) {}
}

class Derived : Base {
        override void foo(Object o) {}
}

is NOT allowed because the mutable thing in derived cannot be passed back to the base interface implicitly.

Perfectly clear; thanks Adam :) !