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Re: Perl/Tk threading and/or cron job?

by liverpole (Monsignor)
on Sep 20, 2011 at 13:55 UTC ( #926946=note: print w/ replies, xml ) Need Help??

in reply to Perl/Tk threading and/or cron job?

Hi PhysiciSteve,

It may help us more if you show what you've tried.

Having said that, I'll give you a very simple example that may do more-or-less what you need. It starts a worker thread which calculates the localtime every minute, and passes that to the main thread through the shared variable $ltime. It's important to keep the Tk code separate from the thread code (because Tk is not thread-safe), which is why the textvariable '$lbl_label' was kept separate from $ltime, and only assigned from $ltime from within the Tk idle loop update_gui().

You can, of course, change sleep 60; to a smaller interval to see it update more often:

#!/usr/bin/perl -w # Libraries use warnings; use strict; use threads; use threads::shared; use Tk; use Tk::Font; # Shared variables my $ltime : shared = 0; # Globals my $lbl_label = "Started"; # Main Program my $thread = threads->create(\&worker_thread); $thread->detach; create_gui(); # Subroutines sub worker_thread { while (1) { $ltime = localtime(time()); print "Debug> In worker_thread(): Updated localtime to '$ltim +e'\n"; sleep 60; } } sub create_gui { my $mw = new MainWindow(-title => 'Thread example'); my $fr = $mw->Frame->pack(-expand => 1, -fill => 'both'); my $fnt = $mw->Font(-family => 'arial', -size => '12'); my $lbl = $fr->Label(-textvar => \$lbl_label, -background => '#ffe +fb5'); my $btn = $fr->Button(-text => 'Exit (ESC)', -background => 'cyan' +); $btn->configure(-command => sub { exit }, -font => $fnt); $lbl->configure(-font => $fnt); $lbl->pack(-side => 'left'); $btn->pack(-side => 'right'); $mw->bind("<Escape>" => sub { $btn->invoke }); $mw->repeat(1000 => \&update_gui); MainLoop; } sub update_gui { printf "Debug> In update_gui(): %s\n", time(); $lbl_label = $ltime; }


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