Map function class member inside class itself

Question

I have difficulty to map the functions of the class member inside the class itself

#include <functional>
#include <map>
#include <string>

class Foo{
    public:
    void bar() {}
    void jar() {}

    private:
    std::map<std::string, std::function<void(void)>> myMap =
    {
        {"bar", bar},
        {"jar", jar}
    };
};

The compiler says no

Severity Code Description Project File Line Suppression State Suppression State Error (active) E0289 no instance of constructor "std::map<_Kty, _Ty, _Pr, _Alloc>::map [with _Kty=std::string, _Ty=std::function, _Pr=std::less, _Alloc=std::allocator>>]" matches the argument list Stackoverflow C:\Stackoverflow\Foo.h 13

Please help, thank you.

Answer 1

bar and jar are member functions. They take pointer - this as first hidden parameter, you cannot treat them as free-functions. And you cannot just wrap them into function<void(void)> by taking pointers to them - what you are doing now.

You should use std::bind to bind this to member functions (or use lambda expressions):

std::map<std::string, std::function<void(void)> > myMap2 =
{
    {"bar", std::bind(&Foo::bar,this)},
    {"jar", std::bind(&Foo::jar,this)}
};

or store pointers to functions:

std::map<std::string, void (Foo::*)(void) > myMap =
{
    {"bar", &Foo::bar},
    {"jar", &Foo::jar}
};