メソッドのチェック

gistfile1.cpp

#include <iostream>
using namespace std;

struct TestA {
    int needed_method() {
        cout << "test" << endl;
        return 0;
    }
};

struct TestB {
    int test() {
        cout << "test" << endl;
        return 0;
    }
};

struct TestC: public TestA {
    int test() {
        cout << "test" << endl;
        return 0;
    }
};

struct TrueType { char a[1]; };
struct FalseType { char a[2]; };


template <class T> TrueType has_needed_method(typeof(&T::needed_method));
template <class T> FalseType has_needed_method(...);

template <class T> void check_method( const string& test_name ) {
    cout << "# " << test_name << endl;
    cout << ( sizeof(has_needed_method<T>(0)) == sizeof(TrueType) ? "true" : "false" ) << endl;
    cout << endl;
}

int main() {
    
    check_method<int>("int");
    check_method<TestA>("TestA");
    check_method<TestB>("TestB");
    check_method<TestC>("TestC");
    
    return 0;
}