CODEWITHSUNDEEP
c++templatesstatic
Ganesh Kamath - 'Code Frenzy'
Ganesh Kamath - 'Code Frenzy'

Reputation: 5291

How to pass Static member function of a c++ Class to template and invoke the function

I have a C++ program where I am able to call non static functions by calling via object. Calling non-static function:

#include <iostream>
class ClassF {
public:
    void enumerateF() {
        std::cout << "f1\n";
        std::cout << "f2\n";
    }
};

class ClassG {
public:
    void enumerateG() {
        std::cout << "g1\n";
        std::cout << "g2\n";
    }
};

template<typename F, typename FUNC>
void do_work(FUNC g)
{
    F f;
    (f.*g)();
}

int main()
{
    do_work<ClassF >(&ClassF::enumerateF);
    do_work<ClassG >(&ClassG::enumerateG);
    return 0;
}

This gives output:

f1

f2

g1

g2

How to call static function:

#include <iostream>
class ClassF {
public:
    static void enumerateF() {
        std::cout << "f1\n";
        std::cout << "f2\n";
    }
};

class ClassG {
public:
    static void enumerateG() {
        std::cout << "g1\n";
        std::cout << "g2\n";
    }
};

template<typename F, typename FUNC>
void do_work(FUNC g)
{
    (F::*g)();
}

int main()
{
    do_work<ClassF >(&ClassF::enumerateF);
    do_work<ClassG >(&ClassG::enumerateG);
    return 0;
}

This gives error:

Error C2760 syntax error: unexpected token 'identifier', expected ')'

But I don’t know how to call static functions by passing the name of the static function as parameter to a template. Please help

Upvotes: 3

Views: 2510

Answers (1)

songyuanyao
songyuanyao

Reputation: 173044

You can invoke the static member function via the function poitner g directly as

g();

Note that &ClassF::enumerateF constructs a function pointer with type void(*)(), which has become unrelated with the class type ClassF. That means, you don't need the template parameter F as the class type, which has been specified when specifying the static member function. e.g.

template<typename FUNC>
void do_work(FUNC g)
{
    g();
}

and then

do_work(&ClassF::enumerateF);
do_work(&ClassG::enumerateG);

LIVE

Upvotes: 4

Related Questions