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

Hi,

I am currently building a GUI in which I want to elaborate each menu item in a seperate module. This is a fragment of my main program:

use Tk 800;
use Tk::Dialog;
use event;
use icit_messages;

$top = new MainWindow;
$top->title("As2Con Gui"); 
my $frame = $top->Frame(qw/-width 800 -height 300 -background white/)-
+>pack; 

create_gui();
sub create_gui {
    $menubar = $top->Menu;
    $status_menu->command(-label => "~Events",  -command => sub { even
+t_function(\$frame) });
    $status_menu->command(-label => "M~essages",   -command => sub { m
+essages_function(\$frame) });

....

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In module event.pm the function event_function is defined (a fragment): 
sub event_function
{
    my $top = shift;    
    if ($view)
        {
            $view->packForget
        }    
        
        $view = $$top->Frame(qw/-width 800 -height 400 -background whi
+te/)->pack(-expand => 1, -fill => 'both');
...

[download]
In module icit_messages.pm the function messages_function is defined (a fragment): 
sub messages_function
{
   my $top = shift;
   if ($view)
    {
      $view->packForget;
    }    
  $view = $$top->Frame(qw/-width 400 -height 400 -background white/)->
+pack();
...

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The problem is when I select menu item Events everything goes OK in the current window, but when I select menu item Messages after I have selected Events the current window is enlarged and the output of Messages is below the output of Events in the same window. This problem does not occur when I select Messages or Events two times after each other...

What am I doing wrong?

Thanks,
Ton

Replies are listed 'Best First'.
Re: Menu Items & Modules...
by PodMaster (Abbot) on Feb 21, 2005 at 10:27 UTC
    Change event_function(\$frame) into event_function($frame) and avoid using $$top, since $top is already a reference.

    You should also Use strict warnings and diagnostics or die, and you should post a complete code snippet which demonstrates your problem (How (Not) To Ask A Question), as describing what happens with a mysterious module (Tk) is not nearly as useful as demonstrating what happens.

    MJD says "you can't just make shit up and expect the computer to know what you mean, retardo!"
    I run a Win32 PPM repository for perl 5.6.x and 5.8.x -- I take requests (README).
    ** The third rule of perl club is a statement of fact: pod is sexy.

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[select]
      OK I did: but how can I avoid that when clicking on the menu item the frame is constantly being printed out?
[reply]
Re: Menu Items & Modules...
by castaway (Parson) on Feb 21, 2005 at 10:39 UTC
    It looks like you are expecting each of the sub modules to refer to the same instance of the $view variable, this is not the case. event.pm will have $event::view, and icit_messages will have $icit_messages::view, thus the packForget only gets called locally, and when going from one menu item to the other, the previous contents are not forgotten.

    You could either create the $view variable in the main programm, and pass it in to your menu item commands, or instead ask the passed in $top for its children, find out which one is the frame that $view represents, and call packForget on that..

    C.

[reply]
      So in each module I should replace: 
          if ($view){
            $view->packForget;
}

      [download]
      with: 
      ($view) = grep{$_->name eq 'frame'} $$top->children;
    
if ($view){
        $view->packForget;
    }

      [download]
      ...?
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[d/l]
[select]
        However: this doesn't work: 
        sub messages_function
{
    my $top = shift;
    
    @kids = $$top -> children;
    foreach (@kids) {print "Name: ", $_->name, "\n";}
    
#    if ($view)
#        {
#            $view->packForget;
#        }    
            
    ($view) = grep{substr($_->name, 0, 5) eq 'frame'} $$top->children;
    
    if ($view){
            $view->packForget;
            print "icit_messages: ";
            print $view;
            print "\n";
    }        

    $view = $$top->Frame(qw/-width 400 -height 400 -background white/)
+->pack();

}

        [download]
[reply]
[d/l]

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