Unbuffered printing to tk text widget

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

I want to be able to print text to a text widget immediately. So in the below code example, what ends up happening is both text items get printed after the sleep. I want the print that occurs before the sleep to actually happen, then sleep, then print what's after the sleep. Do I need to utilize fileevent for this? Can someone give me an example on how to do this? Many thanks!

use Tk;
$mw = new MainWindow;
$mw->title("Test");
$mw->Label(-text => "Pick an item from the list")->pack;
$frm_versions=$mw->Frame()->pack;
$list=$frm_versions->Listbox(-selectmode=>'single', -width=>0, -height
+=>0);
$list->pack;
$list->insert('end', 'Text', 'MoreText', 'TextityTextText', 'TextyText
+alicious', 'Textathon');
$textarea=$mw->Frame()->pack;
$txt=$textarea->Scrolled("Text", -scrollbars=>'e', -width=>45, -height
+=>10);
$txt->pack;
$mw->Button(-text => "GO!!!!", -command => \&go)->pack(-side => 'botto
+m', -expand => 1, -fill => 'x');

MainLoop();

sub go{
   $listselection=$list->curselection();
   if ($listselection eq "") {
      $todo = "";
    }else {
        $todo=$list->get($listselection);
   }
   $txt -> delete('0.0', 'end');
   if ($todo){
      $txt -> insert('end',"Let's see what you picked...\n\n\n");
      sleep (2);
      $txt -> insert('end',"You picked $todo...\n");
   }else{
      $txt->insert('end',"Please pick something from the list...\n");
      last;
   }
}
[download]

Comment on Unbuffered printing to tk text widget Download Code

Replies are listed 'Best First'.
Re: Unbuffered printing to tk text widget by zentara (Cardinal) on May 23, 2007 at 15:40 UTC
To solve your immediate problem: `$txt -> delete('0.0', 'end'); if ($todo){ $txt -> insert('end',"Let's see what you picked...\n\n\n"); $txt->update;` [download] However, you need to stop using sleep in a gui program. Why? Because what if you have other things going on in the background, in a more complex script? sleep will stop them all from functioning for 2 seconds. sleep puts the WHOLE script to sleep. Use this: `# sleep (2); $mw->after(2000); #milliseconds` [download] I'm not really a human, but I play one on earth. Cogito ergo sum a bum	[reply] [d/l] [select]
Re^2: Unbuffered printing to tk text widget by banango (Initiate) on May 23, 2007 at 16:50 UTC
thank you both! the update statement worked!! The sleep was just in there as an example.. to represent "do stuff"... I don't actually have a sleep in my script. thanks again!!	[reply]
Re: Unbuffered printing to tk text widget by johngg (Canon) on May 23, 2007 at 15:23 UTC
If memory serves, there's a `$widget->update()` method that you might be able to apply. Cheers, JohnGG	[reply] [d/l]