in reply to Checkbutton in a loop

What do you expect $j to be when the callback function gets called?  You have to somehow pass it as an argument to the routine.  There are two ways to pass the value:

Either specify an array(ref) to the -command option 

...
for my $i (0...$#a)
{
    $f->Checkbutton(-text => $a[$i], -command => [ \&fun, $i ] )->pack
+();
}
MainLoop;

sub fun
{
    my $j = shift;
    print $a[$j];
}

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Or use a closure 

...
for my $i (0...$#a)
{
    $f->Checkbutton(-text => $a[$i], -command => sub { fun($i) } )->pa
+ck();
}
...

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Re^2: Checkbutton in a loop
by Anonymous Monk on Apr 29, 2012 at 09:27 UTC

    There is a third option, don't pass it any arguments 

    use Tk;
$mw = tkinit;
for(1..4){
    $mw->Checkbutton(
        -text => qq/check it $_/,
        -command => \&f,
    ) ->pack;
}
MainLoop;
sub f {
    my $b = $Tk::event->W;
    warn join q/ /, $b->{Value}, $b->cget(q/-text/);
}
__END__
1 check it 3 at - line 14.
0 check it 3 at - line 14.
1 check it 3 at - line 14.
0 check it 3 at - line 14.
1 check it 3 at - line 14.
0 check it 3 at - line 14.
1 check it 3 at - line 14.
0 check it 3 at - line 14.

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