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

Building on jrok's answer, I have avoided using nested template classes and/or functions.

#include 

#define CHECK_NESTED_FUNC(fName) \
    template > \
    struct _has_##fName \
    : public std::false_type {}; \
    \
    template  \
    struct _has_##fName().fName(std::declval()...))>> \
    : public std::is_same().fName(std::declval()...)), Ret> \
    {}; \
    \
    template  \
    using has_##fName = _has_##fName;

#define HAS_NESTED_FUNC(Class, Func, Signature) has_##Func::value

We can use the above macros as below:

class Foo
{
public:
    void Bar(int, const char *) {}
};

CHECK_NESTED_FUNC(Bar);  // generate required metafunctions

int main()
{
    using namespace std;
    cout << boolalpha
         << HAS_NESTED_FUNC(Foo, Bar, void(int, const char *))  // prints true
         << endl;
    return 0;
}

Suggestions are welcome.