Complete Over-Use of Functor Templates (Academic Experiment), C++ (gcc)

Complete Over-Use of Functor Templates (Academic Experiment)

#include <functional>
#include <iostream>
#include <vector>

struct base_functor
{
    virtual ~base_functor() {}
    virtual void operator()() = 0;
};

template< typename TARGET, typename RESULT, typename... ARGS>
struct derived_functor : base_functor
{
    derived_functor(TARGET* ptr, RESULT (TARGET::*pmfn)(ARGS...), ARGS... data)
       : fun(std::bind( pmfn, ptr, data...)) {}

derived_functor(TARGET& ref, RESULT (TARGET::*pmfn)(ARGS...), ARGS... data)
       : fun(std::bind(pmfn, ref, data... )) {}

virtual void operator()() override { fun(); }

private: std::function< void() > fun;
};

template<typename T, typename R, typename... ARGS> inline // helper to deduce the types
derived_functor<T,R,ARGS...> make_fun(T* p,  R(T::*pmf)(ARGS...), ARGS... data)
{ return derived_functor<T,R,ARGS...>(p, pmf, data... ); }

template<typename T, typename R, typename... ARGS> inline // helper to deduce the types
derived_functor<T,R,ARGS...> make_fun(T& r,  R(T::*pmf)(ARGS...), ARGS... data)
{ return derived_functor<T,R,ARGS...>( r, pmf, data...); }

int main()
{
    struct test
    {
        int foo(int, char) { std::cout << "int test::foo(int,char)" << std::endl; return 9; }
        void bar(long, double, test) { std::cout << "void test::bar(long,double,test)" << std::endl; }
    } test_it, another ;

auto f1 = make_fun(&test_it, &test::foo, 7, 'a');
    auto f2 = make_fun(test_it, &test::bar, 7L, 0.0, another);

std::vector<std::reference_wrapper<base_functor>> functors = { f1, f2 };
    for(auto& fn : functors) fn();
}


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