---
name: "Tk::Item"
section: "3pm"
platform: "linux"
package: "perl-tk"
version: "1:804.027-7"
release: "Debian 4.0 (Etch)"
platforms: ["linux"]
url: "https://new.carta.tech/Tk::Item"
---

# Tk::Item(3pm)

Base class for Menu items

## 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'.