Menu::Item(3pm)
NAME
Tk::Menu::Item - Base class for Menu items
SYNOPSIS
require Tk::Menu::Item;
my $but = $menu->Button(...);
$but->configure(...);
my $what = $but->cget();
package Whatever;
require Tk::Menu::Item;
@ISA = qw(Tk::Menu::Item);
sub PreInit
{
my ($class,$menu,$info) = @_;
$info->{'-xxxxx'} = ...
my $y = delete $info->{'-yyyy'};
}
DESCRIPTION
Tk::Menu::Item is the base class from which Tk::Menu::Button,
Tk::Menu::Cascade, Tk::Menu::Radiobutton and Tk::Menu::Checkbutton are
derived. There is also a Tk::Menu::Separator.
Constructors are declared so that $menu->Button(...) etc. do what you
would expect.
- The "-label" option is pre-processed allowing ~ to be prefixed to the
character to derive a "-underline" value. Thus - $menu->Button(-label => 'Goto ~Home',...)
- is equivalent to
- $menu->Button(-label => 'Goto Home', -underline => 6, ...)
- The "Cascade" menu item creates a sub-menu and accepts these options:
- -menuitems
- A list of items for the sub-menu. Within this list (which is also
accepted by Menu and Menubutton) the first two elements of each
item should be the "constructor" name and the label:
-menuitems => [[Button => '~Quit', -command => [destroy => $mw]], [Checkbutton => '~Oil', -variable => \$oil],] - -postcommand
- A callback to be invoked before posting the menu.
- -tearoff
- Specifies whether sub-menu can be torn-off or not.
- -menuvar
- Scalar reference that will be set to the newly-created sub-menu.
- The returned object is currently a blessed reference to an array of two
items: the containing Menu and the 'label'. Methods "configure" and
"cget" are mapped onto underlying "entryconfigure" and "entrycget". - The main purpose of the OO interface is to allow derived item classes
to be defined which pre-set the options used to create a more basic
item.
BUGS
This OO interface is very new. Using the label as the "key" is a
problem for separaror items which don't have one. The alternative would
be to use an index into the menu but that is a problem if items are
deleted (or inserted other than at the end).
- There should probably be a PostInit entry point too, or a more widget
like defered 'configure'.