Can I use member function as first argument to EnumWindows [duplicate]

Question

Can I use member function as first argument to EnumWindows? I don't see any workaround in this case even with boost::bind.

Answer 1

Given this normal callback function:

BOOL CALLBACK EnumWindowsProc(HWND wnd, LPARAM lParam);

You can invoke EnumWindows using lParam to pass it a pointer to your class:

EnumWindows(EnumWindowsProc, reinterpret_cast<LPARAM>(this));

In EnumWindowsProc you can simply call member function (casting lParam to your class type). Like this:

BOOL CALLBACK EnumWindowsProc(HWND wnd, LPARAM lParam)
{
    return reinterpret_cast<MyClass*>(lParam)->EnumWindows(wnd);
}

If you don't want to make your class method public you can:

• Pack a struct to contain both class instance and pointer to member.
• Use a library for delegates.
• Use boost std:bind (in this case it'll work well because you do it on your own class member, it has not to be __stdcall).

Whatever you will use you can find more details in this post here on SO.