How can I find out whether a Tk Toplevel widget has been destroyed?

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

Currently I'm running a complicated book keeping to monitor the status of open toplevel windows. Can I establish just looking at the variable pointing to the window whether the user has closed that window? ( in my example by querying $toplevel )

use Tk;

my $mw=new MainWindow;

my $toplevel;

my $toplevel_open=0;

my $status=$mw->Label(-text=>'Toplevel Closed :(')->pack;

sub close_toplevel
{
    return if !$toplevel_open;
    $toplevel->destroy;
    $toplevel_open=0;
    $status->configure(-text=>'Toplevel Closed :(');
}

$mw->Button(-text=>'Open Toplevel',-command=>
    sub {
        ($toplevel=$mw->Toplevel())->OnDestroy(\&close_toplevel);
        $toplevel_open=1;
        $status->configure(-text=>'Toplevel Open :)');
    }
)->pack;

$mw->Button(-text=>'Close Toplevel',-command=>\&close_toplevel)->pack;

MainLoop;
[download]

Comment on How can I find out whether a Tk Toplevel widget has been destroyed? Select or Download Code

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Re: How can I find out whether a Tk Toplevel widget has been destroyed? by Discipulus (Canon) on Feb 18, 2015 at 08:22 UTC
I think you are asking about the Exists method: i'm not an expert but i have use in my Tk Tartaglia's triangle fun - Pascal's triangle fun. Here the relevant part (found in subs: `destroy_tri draw_triangle`): `if (! Exists($top_lvl_win)) { $top_lvl_win= $mw->Toplevel();` [download] See also zentara's example: Re: How do I determine if a Tk window exists? The Exists method is in Widget. HtH L* There are no rules, there are no thumbs.. Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.	[reply] [d/l] [select]
Re^2: How can I find out whether a Tk Toplevel widget has been destroyed? by tkguifan (Scribe) on Feb 18, 2015 at 08:47 UTC
It works for me: `use Tk; my $mw=new MainWindow; my $toplevel; my $toplevel_open=0; my $status=$mw->Label(-text=>'Toplevel Closed :(')->pack; $mw->repeat(1000,sub { $status->configure(-text=>Exists($toplevel)? 'Toplevel Open :)':'Toplevel Closed :('); } ); sub close_toplevel { return if !Exists($toplevel); $toplevel->destroy; } $mw->Button(-text=>'Open Toplevel',-command=> sub { $toplevel=$mw->Toplevel(); } )->pack; $mw->Button(-text=>'Close Toplevel',-command=>\&close_toplevel)->pack; MainLoop;` [download]	[reply] [d/l]