Function pointer to non static class member?

I was just about to ask the same question.

...doesn't seem to work with static access, but it compiles.

[edited by - __fold on November 24, 2003 6:56:04 AM]

That doesn''t quite work with what I have. I tried creating a wgEventClass and make the function pointer to wgEventClas::*EventHandler

but I am getting alot of errors on that one. What is wrong with this?

// Event class

class wgEventClass
{
public:
    wgEventClass() {}
    virtual ~wgEventClass() {}
};

// Typedef of event handler

typedef long (wgEventClass::* MessageHandler) (wgBaseWindow *, HWND hWnd, WPARAM wParam, LPARAM lParam);

// App class

class CSimpleStore : public wgEventClass
{
public:
    CSimpleStore();
    ~CSimpleStore();
    void Run(HINSTANCE hInstance, LPCSTR lpCmdLine);

private:
    // Events

    long OnClose(wgBaseWindow *Wnd, HWND hWnd, WPARAM wParam, LPARAM lParam);
    long OnSettings(wgBaseWindow *Wnd, HWND hWnd, WPARAM wParam, LPARAM lParam);

    BOOL CreateMenu();

    wgMDIWindow *m_Wnd;
    wgMenu       m_Menu;
};

// Create code inside class CSimpleStore

m_Wnd->RegisterEvent(WM_CLOSE, &CSimpleStore::OnClose);

I am not sure what I am doing wrong here.

Toolmaker

---

-Earth is 98% full. Please delete anybody you can.

Might make it easier for us if you told us what the actual errors you''re getting *are*.

In any case, this code should work

void (MyClass::*pt2Member)(void);

class MyClass {
public:
  void testFunc() {
    cout << "MyClass::testFunc" << endl;
  }
};

pt2Member = MyClass::testFunc;

MyClass instance;
(instance.*pt2Member)();

Note the clumsy syntax for calling the method.

Personally I go with a functor rather than a function-pointer when I need member-methods.

Note, by the way, that a pointer to a

void function (void);

free function is not compatible with a pointer to a

void function (void);

method function.

- Neophyte

Interesting.

I do not see how it is possible to have a function pointer to a non-static member function. One reason is which object is the pointer pointing to?

Kuphryn

Rather than writing your own wrapper, have a look at wxWindows. It was designed with Win32 in mind, and has been ported to other environments (GTK, Motif, Photon, etc...).

...
you need a 'this' pointer to call methods (member functions) - you have to use a member function pointer as opposed to a normal function pointer.

You may want to use either Loki::Functor or Boost::function - they provide a generic function wrapper which can make this easier. (Generic functors will be added to C++0x)

...
Loki Example

#include <Loki/Functor.h>

struct wgBaseWindow
	{
	HRESULT OnCreate(HWND hwnd, WPARAM, LPARAM)
		{
		return MessageBox(hwnd, "Test", "Test", MB_OK);
		}
	};
 
int main(int argc, char* argv[])
	{
	typedef Loki::Functor<HRESULT, Loki::TL::MakeTypelist<HWND, WPARAM, LPARAM>::Result> wgMessageHandler;
	wgBaseWindow test;
	wgMessageHandler onCreate(&test, &wgBaseWindow::OnCreate);
	//       HWND, L, W

	onCreate(NULL, 0, 0);
	}

However, OnCreate is invoked /prior/ to CreateWindow returning.

- Magmai Kai Holmlor

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[edited by - Magmai Kai Holmlor on November 24, 2003 12:41:21 PM]

mem_fun<>()

*sighs*

quote:

---

Original post by Anonymous Poster
class myclass{
public:
int func(int);
};

typedef int (myclass::*p)(int);

p= &myclass.func();

myclass eg;

eg.*p(1);

myclass* peg =⪚
peg->*p(1);

---

That''s it.