Re: Interrupting a loop

[choroba]

Under Tk, Ctrl+C no longer sends the INT signal. You can still bind <Control-c> to something, though.

Also, Tk already incorporates a loop: the MainLoop. Looping over short lists is probably OK, but introducing loops that might take a long time to iterate or have a high number of iterations is wrong, you should use Tk->repeat or Tk->after instead, see Tk::after.

#!/usr/bin/perl
use warnings;
use strict;

use Tk;

sub periodically {
    warn "Testing the file existence...\n";
}

my $mw = MainWindow->new(-title => 'Test');

my $repeat = $mw->repeat(1000, \&periodically);

$mw->bind('<Control-c>', sub { $mw->afterCancel($repeat) });

MainLoop();

Update: Added the example.

[etj]

To emphasise a point in choroba's excellent thought: when you want to juggle multiple events (a signal/button-click AND elapsed time), you need to stay in the idiom of the relevant event loop. In Tk, that's why you'd want to do the time-delay with Tk::after, not with sleep, so the event loop can quietly also watch for the button-click etc and react; sleep just suspends the whole process until the OS sends it a SIGALRM.

[cavac]

If there's a lot of data processing, it might also make sense to put it into it's own process (or thread) altogether and control it from the GUI with some kind if interprocess messaging.

[merrymonk]

Thank you. I had not come across Tk->repeat etc before.
So I now have my interruptible Perl Tk app working now.

[merrymonk]

The reason I wanted CNTR-C to work was that the Buttons on my Tk GUI would not respond when the loop was processing.
I now have found that using the Tk repeat for the loop means that I can use the Buttons.
So the solution was even better than I first thought.

[jdporter]

You should be using <br/>, not </br>. TIA. (I fixed your root post already.)