Programming Forums > Application Development > C++

titaniumdecoy · Feb 10th, 2008, 5:17 PM

I would be interested to see the code, if you would care to post it.

Dameon · Feb 10th, 2008, 5:26 PM

Shouldn't this be straightforward using mem_fun from <functional>?

Klarre · Feb 10th, 2008, 5:31 PM

Quote:

Originally Posted by Lakrids

Lol thanks!

But a fellow programmer just pointed me out that in fact, it is possible. And he wrote me code which works. The idea is to make a static wrapper member function which will call the non-static one. It also involves passing a pointer to the object, which is then converted into a void*, and in the member function itself, reconverted into the class's type, which will then be passed to the function as the first argument, the implicit "this". This way the wanted action is performed on the object in question, and always gives accurate results.

Remember, this is C++. Nothing is impossible.

Hehe, creative solutions for teh win!

grumpy · Feb 10th, 2008, 9:34 PM

Quote:

Originally Posted by Lakrids

Lol thanks!

But a fellow programmer just pointed me out that in fact, it is possible. And he wrote me code which works. The idea is to make a static wrapper member function which will call the non-static one. It also involves passing a pointer to the object, which is then converted into a void*, and in the member function itself, reconverted into the class's type, which will then be passed to the function as the first argument, the implicit "this". This way the wanted action is performed on the object in question, and always gives accurate results.

And, if you had read my earlier posts carefully, you would see that I noted you need to do a similar thing (i.e. pass information about the object and about the function to act on it). The only difference, clearly, is that I was not willing to implement it for you.

Game_Ender · Feb 11th, 2008, 9:38 AM

This is also possible with Boost.Bind + Boost.Function. Example:

 cpp Syntax (Toggle Plain Text) 
class button
{
public:
 
    boost::function<void> onClick;
};
 
class player
{
public:
 
    void play();
    void stop();
};
 
button playButton, stopButton;
player thePlayer;
 
void connect()
{
    playButton.onClick = boost::bind(&player::play, &thePlayer);
    stopButton.onClick = boost::bind(&player::stop, &thePlayer);
 
    // Calls player::play() on thePlayer object
    playButton.onClick();
}
class button
{
public:

    boost::function<void> onClick;
};

class player
{
public:

    void play();
    void stop();
};

button playButton, stopButton;
player thePlayer;

void connect()
{
    playButton.onClick = boost::bind(&player::play, &thePlayer);
    stopButton.onClick = boost::bind(&player::stop, &thePlayer);
    
    // Calls player::play() on thePlayer object
    playButton.onClick();
}

Lakrids · Feb 11th, 2008, 1:35 PM

Quote:

And, if you had read my earlier posts carefully, you would see that I noted you need to do a similar thing (i.e. pass information about the object and about the function to act on it). The only difference, clearly, is that I was not willing to implement it for you.

Yes, that's right. But I couldn't resist accepting an already-done code...

As for the boost code, thank you, that could also help me.

As for finally getting to the very bottom of (non-)static member function pointers, here's an excellent site with lots of examples :

http://www.newty.de/fpt/callback.html

Thanks to all for the help!

Feb 10th, 2008, 5:17 PM	#11
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 836 Rep Power: 3	Re: Pointer to member function I would be interested to see the code, if you would care to post it.

Feb 10th, 2008, 5:26 PM	#12
Dameon Troll Join Date: Apr 2005 Location: Texas Posts: 730 Rep Power: 4	Re: Pointer to member function Shouldn't this be straightforward using mem_fun from <functional>? __________________ MD5(sig) = bcef75433db02e9ad9bf81d6f7c5c270

Feb 11th, 2008, 9:38 AM	#15
Game_Ender Professional Programmer Join Date: May 2006 Location: Maryland, USA Posts: 306 Rep Power: 3	Re: Pointer to member function This is also possible with Boost.Bind + Boost.Function. Example: cpp Syntax (Toggle Plain Text) class button { public: boost::function<void> onClick; }; class player { public: void play(); void stop(); }; button playButton, stopButton; player thePlayer; void connect() { playButton.onClick = boost::bind(&player::play, &thePlayer); stopButton.onClick = boost::bind(&player::stop, &thePlayer); // Calls player::play() on thePlayer object playButton.onClick(); } class button { public: boost::function<void> onClick; }; class player { public: void play(); void stop(); }; button playButton, stopButton; player thePlayer; void connect() { playButton.onClick = boost::bind(&player::play, &thePlayer); stopButton.onClick = boost::bind(&player::stop, &thePlayer); // Calls player::play() on thePlayer object playButton.onClick(); } __________________ Robotics @ Maryland AUV Team - Software Lead

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Programming Forums > Application Development > C++

Pointer to member function