(C++ : Template) 기타) SFINAE

Posted by : C++ at May 22, 2021

Category : Cpp

SFINAE(Subtitution Faiure Is Not An Error)

#include <iostream>
using namespace std;

template<typename T>
void foo(T t) { cout << "T" << endl; }
void foo(itn t) { cout << "int" << endl; }
void foo(...) { cout << "..." << endl; }

int main()
{
    foo(3);     // int - exactly matching
}

#include <iostream>
using namespace std;

template<typename T>
void foo(T t) { cout << "T" << endl; }
// void foo(itn t) { cout << "int" << endl; }
void foo(...) { cout << "..." << endl; }

int main()
{
    foo(3);     // T
}

#include <iostream>
using namespace std;

template<typename T>
// void foo(T t) { cout << "T" << endl; }
// void foo(itn t) { cout << "int" << endl; }
void foo(...) { cout << "..." << endl; }

int main()
{
    foo(3);     // ...
}

template<typename T>
void foo(T t) { cout << "T" << endl; }

void foo(...) { cout << "..." << endl; }

int main()
{
    foo(3);     // T
}

template<typename T>
int foo(T t) { cout << "T" << endl; return 0; }

void foo(...) { cout << "..." << endl; }

int main()
{
    foo(3);     // T
}

template<typename T>
typename T::type foo(T t) // int::type foo(int t) - 잘못된 표현이다.
{ 
    cout << "T" << endl; 
    return 0; 
}

void foo(...) { cout << "..." << endl; }

int main()
{
    foo(3);     // 에러가 나올것인가?
    // 에러가 나오지 않고 ...가 호출된다. -> SFINAE
}