item(3)
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::But
ton, 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 pre
fixed 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 "con
structor" name and the label:
-menuitems => [[Button => '~Quit', -command=> [destroy => $mw]],
[Checkbutton => '~Oil', -variable=> il],] - -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'.