TK param passing

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

I would see codes written like this:

$submit->bind('<1>' => sub { Submit($p1, $p2, $p3, $p4, $p5); } );
[download]

The above codes I understand, knowing how many parameters and how to intercept the params in a subroutine.

However I dont understand this code:

$yscroll=$mw->Scrollbar()->pack(-fill=>'y', -side=>'right',);
$yscroll->configure( -command => [ \&ScrollAll, $yscroll, [$p1, $p2, $
+p3, $p4, $p5]]);
sub ScrollAll {
    my ($sb, $wigs, @args) = @_;
        foreach my $w (@$wigs) {
            $w->yview(@args);
        }
}
[download]

Can anyone explain how the params are passed when it is constructed in this manner:
-command => [ \&ScrollAll, $yscroll, [$p1, $p2, $p3, $p4, $p5]]
In the above sub's code my ($sb, $wigs, @args) = @_;
What is assigned to $sb?
What is assigned to $wigs?
Is there any other way of passing params when used with -command?
And can that like be written like:

-command => sub {
    subname ($p1, $p2, $p3, $p4, $p5); 
}
[download]

thanks

Comment on TK param passing Select or Download Code

Replies are listed 'Best First'.
Re: TK param passing by Discipulus (Canon) on Apr 24, 2018 at 07:11 UTC
Hello jsteng, When you specify a callback (this is the magic word to search for) for a Tk action and this callback need arguments you need to pass an anonymous array with the function and it's arguments `-command => [ \&subname, arg1, arg2 ... ]` [download] See it explained in it's own doc: Tk::callbacks In your example, if I understand it correctly `$yscroll` arrives as `$b` in the sub and the anonymous array `[$p1, $p2, $p3, $p4, $p5]` arrives as `$wigs` in the sub. Anyway, as AnonymousMonk telegraphically stated, use `Data::Dump` and it's `dd` method to dump what `@_` is inside of your sub. 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: TK param passing by Anonymous Monk on Apr 24, 2018 at 02:08 UTC
Try It To See?	[reply]