Re: Perl/Tk binding Tab

#!/usr/bin/perl

use strict;
use warnings;
use Tk;

my $mw = MainWindow->new();
my $entry1 = $mw->Entry()->pack();
my $entry2 = $mw->Entry()->pack();
my $entry3 = $mw->Entry()->pack();

my %after = ($entry1 => $entry2,
             $entry2 => $entry1,
          );

$mw -> bind('all','<Tab>',sub{
                ($after{$_[0]} // $_[0])->focus;
            }
            );

$mw->MainLoop();
exit(0);
[download]

Comment on Re: Perl/Tk binding Tab Download Code

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Re^2: Perl/Tk binding Tab by Anonymous Monk on Oct 31, 2018 at 17:25 UTC
It works, thank you. Can you explain this. I am not sure I understand it: `($after{$_[0]} // $_[0])->focus;`	[reply] [d/l]
Re^3: Perl/Tk binding Tab by Tux (Canon) on Oct 31, 2018 at 18:05 UTC
`//` is the defined-or operator. If the left part is undefined, take the right part else take the left part. `my $c = $a // $b;` [download] Is like `my $c = defined $a ? $a : $b;` [download] but easier and chainable `my $x = $a // function ($b) // $ENV{FOO} // $self->bar // 0;` [download] Enjoy, Have FUN! H.Merijn	[reply] [d/l] [select]
Re^3: Perl/Tk binding Tab by zentara (Cardinal) on Oct 31, 2018 at 18:16 UTC
Hi, it may help to know that the calling widget is the first argument $_[0] pass to any Tk callback. This code may show you what is happening. Notice how the Entry widget changes with each Tab. `#!/usr/bin/perl use strict; use warnings; use Tk; my $mw = MainWindow->new(); my $entry1 = $mw->Entry()->pack(); my $entry2 = $mw->Entry()->pack(); my $entry3 = $mw->Entry()->pack(); my %after = ($entry1 => $entry2, $entry2 => $entry1, ); $mw -> bind('all','<Tab>',sub{ print "@_\n"; ($after{$_[0]} // $_[0])->focus; } ); $mw->MainLoop(); exit(0);` [download] I'm not really a human, but I play one on earth. ..... an animated JAPH	[reply] [d/l]