Re: C++-classes.

[Peeter Vois <Peeter Vois mail ee>]

On 18 Oct 2002 09:35:06 +0100
James Durie <jdurie anvil co uk> wrote:

> On Fri, 2002-10-18 at 09:23, David Larsson wrote:
> > Hi.
> >
> > How do you get this to work.
> >
> > /* Class Definition */
> > class GtkClass
> > {
> >   public:
> >     void GtkClass();
> >     void Test();
> >   private:
> >     GtkWidget *button;
> > };
> >
> > GtkClass::GtkClass()
> > {
> >   button=gtk_button_new();
> >
> >   /* The part that doesn't work. */
> >   gtk_signal_connect(GTK_OBJECT(button), "clicked",
> >   GTK_SIGNAL_FUNC(Test), NULL);
> > }
> >
> > How is the Method Test to be declared, and how do you call it from a
> > gtk_signal_connect()?
> >
> > Thanks
> >
> > // David
>
> You can't pass a method in as a callback function pointer. There is a
> hidden parameter, this, to all methods which points to the instance of
> the class.
>
> Instead try:
> gtk_signal_connect(GTK_OBJECT(button), "clicked",
> GTK_SIGNAL_FUNC(clicked_cb), this);

I would like to say that I never used GTK with C++ before but does not following
work? Or something like this:

gtk_signal_connect(GTK_OBJECT(button), "clicked",
        GTK_SIGNAL_FUNC(this->Test), NULL);


> where clicked_cb is:
> void clicked_cb(GtkButton *button, GtkClass *c)
> {
>       c->Test();
> }
>
>
> That is the simplest way to get a callback calling a method and how I
> have done it in my own projects.
>
> James
>
>
> -- 
> James Durie               Phone:  +44 20 7749 7904
> Anvil Software Limited    Fax:    +44 20 7749 7916
> 46-48 Rivington Street    e-mail: jdurie anvil co uk
> London EC2A 3QP
>
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      Peeter Vois
http://my.tele2.ee/vois