I'm a Perl novice and I'm trying to develop my skills by building a small GUI application using wxperl. Although this question does relate to wxperl, I suspect it is equally a fundamental OO question.

I'd like to make use of the wxVListBox control and to do so I understand that I must derive from it a subclass, however this has left me with a couple of questions.

Firstly, the demo code appears to derive from a class called Wx::PlVListBox rather than Wx::VListBox, so I'm not sure which of the two I should be using? I've experimented with both and if I base my subclass on Wx:VListBox the OnDrawItem method doesn't seem to get called.

If I base my subclass on Wx::PlVListBox, the control appears to work as expected but I'm not sure how I go about adding additional attributes given I have no knowledge of how the underlying object is stored? Many thanks for any assistance.

My test code:

#!/usr/bin/perl

use strict;
use warnings;

package MyFrame;
use Wx;
use base qw(Wx::Frame);

sub new
{
    my $class = shift;
    
    my $self = $class->SUPER::new( 
        undef,           # parent window
        -1,              # ID -1 means any
        'wxPerl rules',  # title
        [-1, -1],        # default position
        [100, 200],      # size
    );
    
    my $panel = Wx::Panel->new( 
        $self,            # parent window
        -1,               # ID
    );

    my $vlistbox = MyWxVListBox->new( $self, -1, [-1, -1], [100, 200] 
+);
    return $self;
}

package MyApp;

use base qw(Wx::App);

sub OnInit {

    my $class = shift;
    my $frame = MyFrame->new();
    $frame->Show( 1 );
}

package MyWxVListBox;

use base qw(Wx::PlVListBox);
use Wx;

sub new {

    my( $class, @args ) = @_;
    my $self = $class->SUPER::new( @args );
    $self->SetItemCount( 10 );
    return $self;
}

sub OnDrawItem {

    my( $self, $dc, $rect, $item ) = @_;
    print "Drawing item\n";
    $dc->DrawText( $item, $rect->x + 1, $rect->y + 1);
}

sub OnMeasureItem {
    my( $self, $item ) = @_;
    return 20;
}

package main;

my $app = MyApp->new();
$app->MainLoop;
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