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Re: Callbacks mechanism doesn't handle overloaded functions? [message #37484 is a reply to message #37475]

Wed, 10 October 2012 21:50

mirek
Messages: 14267
Registered: November 2005

Ultimate Member

Peter wrote on Wed, 10 October 2012 15:05

Hi.

I'm a new U++ user with little experience, especially in how the framework important features work internally. That's why I'm not sure if I discovered a bug or merely a framework limitation. Here's a code snippet to demonstrate the problem:

#include <CtrlLib/CtrlLib.h>

using namespace Upp;

class MyWindow : public TopWindow
{
	Button btn;
	
	void Fun() {PromptOK(AsString(5));}
	void Fun(int n){PromptOK(AsString(n));}
	
	public:
	typedef MyWindow CLASSNAME;
	MyWindow()
	{
		btn <<= THISBACK(Fun);
	}
};

GUI_APP_MAIN
{
	MyWindow().Run();
}

In the code above you can see two different, overloaded functions named Fun. When I try to compile it, compiler reports the following error:

error C2668: 'Upp::callback' : ambiguous call to overloaded function

Well, while it is clear that btn.WhenAction is no-parameter Callback, THISBACK(Fun) is evaluated (by compiler) independently of this fact. As such, it is indeed ambiguous whether you mean Callback with no parameters or with single parameter at this point.

Unfortunately, there is no nice solution here (C++ language limitation). You have to name your methods differently...

Mirek

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