jpream has asked for the wisdom of the Perl Monks concerning the following question:

First attempt at creating a mega widget and I can't seem to get the components to take on the default settings. The widget is a frame with two scrolled Listbox and a couple Buttons. I think I have the ConfigSpecs setup correctly, or at least how I've seen it in the books. And the configure method works correctly (only targets the Listboxes with -bg). Can somebody please clue me in to what I'm missing..? Thanks. jpream 
package Tk::SelectBoxes;
use Tk::widgets qw/Listbox Button/;
use base qw(Tk::Frame);
Construct Tk::Widget 'SelectBoxes';

use strict;

sub ClassInit {
   my($class, $mw) = @_;
   $class->SUPER::ClassInit($mw);
   }
sub Populate {
   my ($self,$args) = @_;
   
   $self->SUPER::Populate($args);
   ###########################################
   # Build SBox components
   ###########################################
      my $left_lb = $self->Scrolled("Listbox",
                                          -scrollbars => "osoe",
                                          -selectmode => "extended");
      my $right_lb = $self->Scrolled("Listbox",
                                          -scrollbars => "osoe",
                                          -selectmode => "extended");

      my $left_btn = $self->Button(-text    => '<-',
                                   -command => [$self => 'Box2Box',
                                                $right_lb,
                                                $left_lb]);
      my $right_btn = $self->Button(-text    => '->',
                                    -command => [$self => 'Box2Box',
                                                 $left_lb,
                                                 $right_lb]);

      $left_lb->pack(-side   => "left",
                     -expand => 1,
                     -fill   => "both");
      $right_lb->pack(-side   => "right",
                      -expand => 1,
                      -fill   => "both");
      $right_btn->pack(-anchor => "s",
                       -expand => 1);
      $left_btn->pack(-anchor => "n",
                      -expand => 1);
                      
   #########################################
      $self->ConfigSpecs(
         '-background' => [[$left_lb, $right_lb],
                           'background',
                           'Background' ,
                           'black'],
         'DEFAULT'     => ['DESCENDANTS', 'SELF']);
   }

[download]

janitored by ybiC: Retitle from "ConfigDefault not working?"

Replies are listed 'Best First'.
Re: Tk::widgets ConfigDefault not working?
by zentara (Cardinal) on Nov 14, 2003 at 17:44 UTC
    Hi, I just came accross this by Stephen Lidie about creating a mega-widget, hope it helps. It uses Tk::Derived . 
    #Stephen Lidie wrote:
#There are at least two ways of doing it: ferreting out the actual  
#superclass callback and invoking it manually (not recommended), or  
#creating a proper mega-widget.  The mega-widget method is cleaner and
+  
#seems to do what you want.

#Here is a modified version of the Emu example.  First, note that I  
#added Tk::Derived to the module's base class because we need to turn 
+ 
#this into a first class mega-widget - it's no longer a simple example
+.  
#Second, the <Enter> binding has been deleted from the class  
#initialization method ClassInit().

-------------------------------------------------------------
use Tk;
use strict;

package MyButton;

use base qw/Tk::Derived Tk::Button/;
Construct Tk::Widget 'MyButton';

sub ClassInit {
     my ($class, $mw) = @_;
     $class->SUPER::ClassInit($mw);
#    $mw->bind($class, '<Enter>', sub{print "Entered a MyButton\n"});
}

sub Populate {
     my ($self, $args) = @_;
     $self->SUPER::Populate($args);
     $self->bind('<Enter>', sub{print "Entered a MyButton\n"});
#    my (@bt) = $self->bindtags;
#    $self->bindtags( [ @bt[ 1, 0, 2, 3 ] ] );
}

1;

package main;

my $mw = MainWindow->new;
$mw->Button(-text => 'NormalButton')->pack;
$mw->MyButton(-text => 'MyButton')->pack;

MainLoop;
#--------------------------------------------------------------

#The real change is the addition of Populate(), the class instance  
#constructor. It's responsible for creating the <Enter> binding.  Now 
+ 
#when you <Enter> a MyButton mega-widget it behaves exactly as a norma
+l  
#Button does, plus, it prints a message.

    [download]
[reply]
[d/l]

Back to Seekers of Perl Wisdom