#include <iostream>
#include <functional>
using namespace std;
using namespace std::placeholders;

bool check1(int a, int b) { return a + b > 0; }
bool check2(int a, double b) { return a + b > 0; }
bool check3(int a) { return a > 0; }

struct AlwaysTrue {
    bool operator()(int i) const {
        return true;
    }
};

template <class FClass = AlwaysTrue>
bool Foo(FClass foo = FClass()) {
    for (int i = 0; i < 3; ++i) {
        cout << foo(i) << " ";
    }
    cout << endl;
}

int main() {
    Foo(std::bind(check1, _1, 0));
    Foo(std::bind(check2, _1, .0));
    Foo(std::bind(check3, _1));
    Foo();
    return 0;
}