RE: Using global variables for widgets

["Childers, Matthew" <mchilders bentonville k12 ar us>]

Thanks for all the replies.  I will definitely check into these, I knew
there had to be a way.

Thanks again,
Matt

-----Original Message-----
From: Markus Lausser [mailto:sgop users sourceforge net] 
Sent: Friday, March 28, 2003 12:32 PM
To: Childers, Matthew
Cc: gtk-app-devel-list gnome org
Subject: Re: Using global variables for widgets

On Fri, Mar 28, 2003 at 12:03:10PM -0600, Childers, Matthew wrote:
> I am new to C programming and GTK so please bear with me.  I took a C
> programming class in college where my instructor would not let us
create
> global variables in any program we wrote.  We were to create them in
the
> function they were used in and pass a pointer to any other functions
> they were needed in.  He explained that this was good programming
> practice and that there were times when global variables were useful,
> but not in any of the programs we were writing.
>  
> Now, three years later I have taken up C again (dusting off the old
> textbooks) and am getting into GTK.  I have been playing around with
> test programs and need some program design advice.  I have a couple
> widgets that when I press a button, I want them to disappear.
However,
> with the g_signal_connect function, I can't seem to find a way to pass
a
> pointer of each of these widgets that I want hidden.  What I end up
> doing is creating a global variable for each widget that I want hidden
> and hiding them with a callback function.

I would suggest several solutions:
1) pack all widgets you like to hide into a struct and pass it as
   data pointer to your callback function (instead of NULL)
2) attach the widget pointers to your button with
   g_object_set_data(G_OBJECT(button), "widget1", widget1);
   In the callback you can access them again with:
   widget1 = g_object_get_data(G_OBJECT(button), "widget1");
   With gtk 1.x you would use gtk_object_(g/s)et_data();
3) Make the widgets static in the .c file and put both the callback
   and the function that creates your widgets there.
4) put all widgets you want to hide in a container (GtkHBox, etc) if
   possible and simply pass the container to your callback and hide it.
  
I personally would perfer solution 4) if possible, if not then i'd use
2)
I dont like 1) cause an additional struct is needed (de/allocation).

Markus.