amdme127 has asked for the wisdom of the Perl Monks concerning the following question:

I am trying to create a Perl program (Perl Tk GUI) that runs different scripts based on what users choose out of a menu at the top. The scripts output text progress and feedback based on records that the script processed into a Scrolled widget/element. I want to be able to forget/destroy/delete the widget when I move to a new option in the menu so I can create a fresh one to output text from the next script the user will run.

my $mainFrame = $mw->Frame()->pack(-side=>'top');

my $tx = $mainFrame->Scrolled(qw/Text 
    -font normal
        -width 73
    -height 15
    -wrap word 
    -scrollbars e/);
$tx->pack;

tie *STDOUT, 'Tk::Text', $tx;

#script is called, runs, outputs to Scrolled above, user chooses new o
+ption and sub clear() is called:

sub clear{
      $mainFrame ->destroy();
      $tx ->pack('forget'); 
}

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I want the $tx widget to disappear/clear off the screen

I have tried multiple things like forget, destroy, delete and anything else I could find on this site and around the interwebs. Some of them don't throw errors at all, but when I go to run a different script, the Scrolled widget/element will not clear from the screen so the new one shows up below the old one. I am relatively new to Perl GUI programming (this is my first GUI with Perl and I am trying to learn it as I go) so go easy on me

</code>

Replies are listed 'Best First'.
Re: Perl Tk Forgetting a Widget
by zentara (Cardinal) on Oct 14, 2011 at 12:54 UTC
    You are close, your use of packForget is wrong. There is no pack('forget'). Also you need to watch your memory when destroying widgets, Tk has a nasty habit of leaving refcounts around which cause memory gains over time. So try to reuse the $tx variable. Here is how I would do it. Don't destroy the Frame, as that causes an unpleasant window size change. 
    #!/usr/bin/perl
use warnings;
use strict;
use Tk;

my $mw = MainWindow->new;

my $mainFrame = $mw->Frame()->pack(-side=>'top');

my $tx; # reuse global to prevent memory gains
rebuild(); #setup first use

# script is called, runs, outputs to Scrolled above, user 
# chooses new option and sub clear() is called:
my $button = $mw->Button(-text=> 'Clear',
             -command => \&clear
   )->pack();

my $button1 = $mw->Button(-text=> 'Rebuild',
             -command => \&rebuild
   )->pack();


MainLoop;

sub clear{
       #$mainFrame ->destroy(); # don't, causes screen jitter
       $tx->packForget;
       # $tx ->pack('forget'); #wrong usage 
       
           #clean out a top level
#    my @w = $tl->packSlaves;
#    foreach (@w) { $_->packForget; }
       
}

sub rebuild{

$tx = $mainFrame->Scrolled(qw/Text 
    -font normal
        -width 73
    -height 15
    -wrap word 
    -scrollbars e/);
$tx->pack;

tie *STDOUT, 'Tk::Text', $tx;

print "foobar!".time."\n";
}

    [download]
    I'm not really a human, but I play one on earth.
    Old Perl Programmer Haiku ................... flash japh
[reply]
[d/l]

      I agree re Tk's nasty habits. I don't understand the desire to destroy/recreate or forget/repack. Why not just clear all the text from the widget?

      sub clear {
  $tx->delete('1.0','end');
}

      [download]
[reply]
[d/l]
        Why not just clear all the text from the widget?

        So he could rebuild another page for that Frame, perhaps a Canvas with a chart on it?

        I'm not really a human, but I play one on earth.
        Old Perl Programmer Haiku ................... flash japh
[reply]
Re: Perl Tk Forgetting a Widget
by Khen1950fx (Canon) on Oct 14, 2011 at 03:04 UTC
    Using a simple example of an exit callback: 
    #!/usr/bin/perl

use strict;
use warnings;
use Tk;

my $mw = MainWindow->new;
fill_window($mw, 'Main');
my $top1 = $mw->Frame;
fill_window($top1, 'First Frame');

my $tx = $mw->Scrolled('Text', 
    -font => 'normal',
    -width => '73',
    -height => '15',
    -wrap => 'word', 
    -scrollbars => 'e');
$tx->pack;
tie *STDOUT, 'Tk::Text', $tx;

MainLoop;

sub fill_window{
      my ($window, $header) = @_;
      $window->Label(-text => $header)->pack;
      $window->Button(
          '-text' => 'forget',
          '-command' => [$mw => 'destroy']
      )->pack('-side' => 'right'); 
}

    [download]
[reply]
[d/l]
Re: Perl Tk Forgetting a Widget
by priyaviswam (Sexton) on Oct 14, 2011 at 07:31 UTC

    Make the variable $tx as global and try destroy I have tried similar scenario with the checkbuttons it worked.

[reply]

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