language: C++11 (gcc-4.7.2)
date: 193 days 17 hours ago
link:
visibility: private 
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#include <type_traits>
#include <iostream>
 
struct test1 {
    void Invoke() {};
};
 
struct test2 {
    template<typename> void Invoke() {};
};
 
 
enum class InvokableKind {
    NOT_INVOKABLE,
    INVOKABLE_FUNCTION,
    INVOKABLE_FUNCTION_TEMPLATE
};
 
template<typename Functor, class Enable = void>
struct get_invokable_kind {
    const static InvokableKind value = InvokableKind::NOT_INVOKABLE;
};
 
template<typename Functor>
struct get_invokable_kind<
  Functor,
  decltype(Functor().Invoke())
  >
{
    const static InvokableKind value = InvokableKind::INVOKABLE_FUNCTION;
};
 
template<typename Functor>
struct get_invokable_kind<
  Functor,
  decltype(Functor().Invoke<void>())
  >
{
    const static InvokableKind value = InvokableKind::INVOKABLE_FUNCTION_TEMPLATE;
};
 
 
int main() {
    using namespace std;
 
    cout << (get_invokable_kind<test1>::value == InvokableKind::INVOKABLE_FUNCTION) << endl;
    cout << (get_invokable_kind<test2>::value == InvokableKind::INVOKABLE_FUNCTION_TEMPLATE) << endl;
 
}
 
prog.cpp:37:3: error: template argument 2 is invalid