[Chapter 18] 18.6 The Radiobutton Widget
Author: Ellen Siever, Stephen Spainhour & Nathan Patwardhan
Date: 1999-07-02T01:58:52Z

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| Chapter 18 Perl/Tk |

## 18.6 The Radiobutton Widget

Create a radiobutton with the `Radiobutton` method. A radiobutton has an indicator to the left of the label indicating whether the button is selected. It differs from a checkbutton in that only one button may be selected at the same time. Each button in a group of radiobuttons uses the same variable specified with the `-variable` option; when selected, the button assigns that variable the value specified by the `-value` option.

>     $parentwidget->Radiobutton (options)

The standard configuration options that apply to `Radiobutton` are: `-activebackground`, `-activeforeground`, `-anchor`, `-background`, `-bg`, `-bitmap`, `-borderwidth`, `-bd`, `-cursor`, `-disabledforeground`, `-font`, `-foreground`, `-fg`, `-height`, `-highlightbackground`, `-highlightcolor`, `-highlightthickness`, `-image`, `-justify`, `-padx`, `-pady`, `-relief`, `-underline`, `-width`, and `-wraplength`.

Other options are:

`-command =>` `callback`

  Pointer to a function that will be called when the radiobutton is pressed.

`-indicatoron =>` `boolean`

  Determines whether or not to display the indicator. Default is on (1).

`-selectcolor =>` `color`

  Color of the indicator when the radiobutton is on.

`-selectimage =>` `imgptr`

  Defines the image to be displayed instead of text when the radiobutton is on. Ignored if `-image` is not used.

`-text =>` '`text`'

  Defines the text string displayed in the radiobutton. See also `-textvariable`.

`-textvariable =>` `\$variable`

  Points to the variable containing text to be displayed in the radiobutton. Button text will change as `$variable` does.

`-value =>` `value`

  Sets `$variable` to the specified value when the radiobutton is selected (default is 1).

`-variable =>` `\$variable`

  Associates the on/off value of the indicator with the specified variable.

### 18.6.1 Radiobutton Methods

In addition to `configure` and `cget`, the following methods are supported by `Radiobutton`:

`deselect`

  Deselects the button and sets the variable to the empty string.

`select`

  Sets the radio button.

`flash`

  Causes the button to flash from the normal to active state colors.

`invoke`

  Selects the button and invokes the callback command as if the radiobutton were clicked.

18.5 The Checkbutton Widget |  | 18.7 The Label Widget