Re: [perl-win32-gui-users] How to pass $_ to a subroutine

[Robert May]

Perl Rob wrote:

[slightly edited]
foreach ( @button_names ) {
    my ($name) = $_;
    $main->AddButton(
                   -name    => $name,
                   -text    => $name,
                   -onClick => sub { Button_Clicked ( $name ) },
                     ...
    );
}
 
sub Button_Clicked {
     print "Your name is " . $_[0];
}

So, what you're really like is:

foreach (@button_names) {
        $main->AddButton(
                -name => $_,
                -text => $_,
                -onClick => \&clicked,
                ...
);

# NEM callback
sub clicked {
        my ($self) = @_;

        print $self->GetName(), "\n";

        return 1;
}

But there is no GetName() method for the button object (or indeed any 
Win32::GUI object).  Slightly naughty, and I shouldn't be encouraging 
this [1], but the object's name is stored in it's '-name' hash slot, so 
you can replace:
        print $self->GetName(), "\n";
with
        print $self->{-name}, "\n";
And get what you want without the closures.

But why do you need the name, given that the NEM callback gives you the 
object reference as first parameter?


Regards,
Rob.

[1] Accessing an object's internal state by any mechanism other than an 
accessor method should be strongly discouraged, as it breaks the OO 
encapsulation.