Check if a class has a member function of a given signature

Question

I\'m asking for a template trick to detect if a class has a specific member function of a given signature.

The problem is similar to the one cited here http://www.go

Answer 1

Here is a simpler take on Mike Kinghan's answer. This will detect inherited methods. It will also check for the exact signature (unlike jrok's approach which allows argument conversions).

template 
class HasGreetMethod
{
    template 
    static std::true_type testSignature(void (T::*)(const char*) const);

    template 
    static decltype(testSignature(&T::greet)) test(std::nullptr_t);

    template 
    static std::false_type test(...);

public:
    using type = decltype(test(nullptr));
    static const bool value = type::value;
};

struct A { void greet(const char* name) const; };
struct Derived : A { };
static_assert(HasGreetMethod::value, "");

Runnable example