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=head1 NAME
Tk::Derived - Base class for widgets derived from others
=for pm Tk/Derived.pm
=for category Derived Widgets
=head1 SYNOPSIS
package Tk::MyNewWidget;
use Tk::widgets qw/ BaseWidget, list of Tk widgets /;
use base qw/ Tk::Derived Tk::BaseWidget /;
Construct Tk::Widget 'MyNewWidget';
sub ClassInit {
my( $class, $mw ) = @_;
#... e.g., class bindings here ...
$class->SUPER::ClassInit( $mw );
}
sub Populate {
my( $self, $args ) = @_;
my $flag = delete $args->{-flag};
if( defined $flag ) {
# handle -flag => xxx which can only be done at create
# time the delete above ensures that new() does not try
# and do $self->configure( -flag => xxx );
}
$self->SUPER::Populate( $args );
$self = $self->Component( ... );
$self->Delegates( ... );
$self->ConfigSpecs(
'-cursor' => [ SELF, 'cursor', 'Cursor', undef ],
'-something' => [ METHOD, dbName, dbClass, default ],
'-text' => [ $label, dbName, dbClass, default ],
'-heading' => [ {-text => $head},
heading, Heading, 'My Heading' ],
);
}
sub something {
my( $self, $value) = @_;
if ( @_ > 1 ) {
# set it
}
return # current value
}
=head1 DESCRIPTION
Tk::Derived is used with Perl's multiple inheritance to override some
methods normally inherited from Tk::Widget.
Tk::Derived should precede any Tk widgets in the class's base class
definition.
Tk::Derived's main purpose is to apply wrappers to C<configure> and C<cget>
methods of widgets to allow the derived widget to add to or modify behaviour
of the configure options supported by the base widget.
The derived class should normally override the C<Populate> method provided
by Tk::Derived and call C<ConfigSpecs> to declare configure options.
The public methods provided by Tk::Derived are as follows:
=over 4
=item -E<gt>ConfigSpecs(-I<key> =E<gt> [I<kind>, I<name>, I<Class>, I<default>], ...)
=back
=head1 SEE ALSO
L<Tk::ConfigSpecs|Tk::ConfigSpecs>
L<Tk::mega|Tk::mega>
L<Tk::composite|Tk::composite>
=cut
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