It means repeat every 0 ms, which is not doable in the real world, unless the task does not take time.

In the world of computer, the code sucked up all CPU cycles, and the GUI never got a chance to be displayed.

Modify the update function a little bit, run it, and we will see that the code actually runs, as we get all those "here". But that is the only thing the code has a chance to do.

use Tk;
use strict;

my $init = 0;
my $display = 0;

my $mw = MainWindow->new;
$mw->geometry("300x100");

my $menubar = $mw->Frame()->pack(-side => 'left');

my $mainframe = $mw->Frame(-bg => 'darkblue', -container => 0);
$mainframe->pack(-fill => 'both', -side => 'top', -expand => 1);

$menubar->Button(-text => "Start", -command => \&start)->pack(-side =>
+ "left");
$menubar->Button(-text => "Stop", -command => \&stop)->pack(-side => "
+left");
$menubar->Button(-text => "Reset", -command => \&reset)->pack(-side =>
+ "left");

my $abc = $mainframe->Label(-textvariable => \$display);
$abc->pack;
$abc->repeat($display, \&update);
MainLoop;

sub start {
$init=1;
}

sub stop {
$init=0;
}

sub reset {
$init=0;
$display=0;
}

sub update {
#if ($init==1){
    print "here\n";
$display++;
#}
}

[download]

In reply to Re: Re: Tk not functioning if variable is zero by pg
in thread Tk not functioning if variable is zero by pseudosocrates

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