Re: Connecting signals syntax.

[German Diago Gomez <al059365 alumail uji es>]

Mensaje citado por Murray Cumming <murrayc murrayc com>:

> On Sat, 2007-01-13 at 15:22 +0100, German Diago Gomez wrote:
> > 
> >  Hello. I'm using gtkmm to build an application. Great work! A good GUI
> > toolkit.
> >  But I'd like to give some feedback of what, from my perspective, would be
> some
> > little improvements to the API.
> >  When I want to connect some signal to a slot, I think the syntax should
> be
> > clearer. Why have I to do:
> > 
> >    button.signal_clicked().connect(sigc::mem_fun(this, &MyClass::myFunc));
> >    button.signal_clicked().connect(sigc::ptr_fun(&myFunc));
> > 
> > When I could do:
> > 
> >    button.signal_clicked().connect(this, &MyClass::myFunc);
> 
> This might be possible already with libgsigc++. If not then I wonder how
> boost::signal achieves it.
> 
> >    button.signal_clicked().connect(&myFunc);
> 
> I think this is possible already.
> 
> > But the thing gets worse when you combine that with bind:
> >  
> >    button.signal_clicked().connect(boost::bind(sigc::mem_fun(this,
> > &MyClass::myFunc), data));
> > 
> > This is difficult to write. I always have to think carefully what I'm
> writing.
> > Otherwise I make mistakes.
> 
> I find that spaces or newlines help.
> 
> >   I think that sigc should be replaced by boost::function which is more
> powerful
> > and you haven't to deal explicitly with mem_fun and ptr_fun because it has
> a
> > better type deduction system.
> 
> libsigc++ and boost::signal are very similar because they have tried to
> be similar, influencing each other, and avoiding unnecessary
> differences. Today libsigc++ is really just "like boost::signal but with
> an officially stable API/ABI.".
> 
> When signals are in the official C++ standard, and are widely available,
> I expect that we will port gtkmm to it.
> 
> >   And I think that instead of using bind, you could overload connect to
> receive
> > additional parameters until an arbitrary number. This would make the
> syntax
> > like this:
> > 
> >   button.signal_clicked().connect(this, &MyClass::myFunc, data1, data2);
> > 
> >  You could do this for an arbitrary number of arguments, say, 10 arguments
> for
> > example. I think that syntax matters because you have to deal with
> connections
> > in code since the signaling system is type-safe and you can't do it from
> glade
> > like in python or C.
> > 
> >  Don't get me wrong, I think gtkmm is a good toolkit, but I think that
> doing
> > what I'm suggesting would be an improvement in API usability.
> 
> -- 
> Murray Cumming
> murrayc murrayc com
> www.murrayc.com
> www.openismus.com
> 
> 



> 
> I think this is possible already.

> >    button.signal_clicked().connect(this, &MyClass::myFunc);
> 
> This might be possible already with libgsigc++. If not then I wonder how
> boost::signal achieves it.
> 
> >    button.signal_clicked().connect(&myFunc);
> 
> I think this is possible already.

I tried both in my code and the second way works, but not the first, which is
the most commonly used for me. :-(
I think this is a libsigc++ issue then :-(.
I looked at the signals documentation in gtkmm documentation and the only
documented way to connect a free function is with sigc::ptr_fun, so it might be
updated :-). I didn't know even of the possibility to do that.

Thanks for your help and your time.