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

I'm not sure if I understand you correctly, but you may exploit SFINAE to detect function presence at compile-time. Example from my code (tests if class has member function size_t used_memory() const).

template
struct HasUsedMemoryMethod
{
    template struct SFINAE {};
    template static char Test(SFINAE*);
    template static int Test(...);
    static const bool Has = sizeof(Test(0)) == sizeof(char);
};

template
void ReportMemUsage(const TMap& m, std::true_type)
{
        // We may call used_memory() on m here.
}
template
void ReportMemUsage(const TMap&, std::false_type)
{
}
template
void ReportMemUsage(const TMap& m)
{
    ReportMemUsage(m, 
        std::integral_constant::Has>());
}