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Re: perl/Tk Entry widget displays wrong value when -textvariable is shared

by zentara (Archbishop)
on Sep 02, 2010 at 17:30 UTC ( #858613=note: print w/ replies, xml ) Need Help??


in reply to perl/Tk Entry widget displays wrong value when -textvariable is shared

You are ecncountering a problem with threads:shared hashes where only the first level keys get shared by default. When you run as shared, the $top_hash{A}{B} gets ignored as being shared, while it runs fine in normal perl.

To amplify a bit, the Tk eventloop will never respond to a change in threads shared variables, when they are across thread boundaries. You don't have actual threads here, but you need to setup a timer, to read for any changes in the shared variable. So you can't use tied variables effectively across threads without timers. Try this:

#!/usr/bin/perl use warnings; use strict; use threads; use threads::shared; use Tk; my %top_hash; share $top_hash{'A'}{'B'}; $top_hash{'A'}{'B'} = 'Original'; my $t = MainWindow->new()->Scrolled('Text')->pack(); my $e = $t->Entry(-textvariable => \$top_hash{'A'}{'B'}); $t->windowCreate('end', -window => $e); $t->insert('end', "\n"); my $timer = $t->after(3000,sub{$top_hash{'A'}{'B'} = 'Changed'}); MainLoop;

I'm not really a human, but I play one on earth.
Old Perl Programmer Haiku ................... flash japh


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