I don't know what structural subtyping is, but I no that Go's interfaces are not...

dan00 · on July 27, 2012

    class A { public: int do() { return 1; } };
    class B { public: int do() { return 2; } };
    
    template <typename T> int do(T t) { return t.do(); }

Olreich · on July 27, 2012

How does one use that template? Can you show me a function that takes anything with a do() method? Like this?:

    do<A>(a)
    do<B>(b)

Can I take any arbitrary type with an "int do()" method and use that with do? Like:

    do(Arbitrary)

dan00 · on July 27, 2012

"How does one use that template? Can you show me a function that takes anything with a do() method? Like this?:"

It should work without the template parameter: do(a), do(b)

"Can I take any arbitrary type with an "int do()" method and use that with do?"

Yes.

Olreich · on July 27, 2012

masklinn · on July 27, 2012

As dan00 noted, it works without the template as long as there is no ambiguity. If there's an ambiguity (a template function defined on <int, int> and <double, double> to which you provide an int and a double) then you have to use explicit template parameter to specify which overload will be used.

It's not the case here, so it just works.

masklinn · on July 27, 2012

> I don't know what structural subtyping is

Which is why "you have never seen a language doing interfaces like Go", everybody else calls it what it is (structural typing/structural subtyping)

> I no that Go's interfaces are nothing like anything in C++

Well you may "know" it, but your knowledge is wrong.