radio button's

> I am having some trouble getting radio buttons to work. Basically I have
> a instance variable in my model which can take three possible values:
> #red, #green or #blue. I would like to use radio buttons to change the
> value of the instance var, but I don't understand how to do this since
> the radio button expects to be coupled to a boolean.
>
> Best Regards,
>
>
> Frank
>

> Frank,
>
>
>>I am having some trouble getting radio buttons to work. Basically I have
>>a instance variable in my model which can take three possible values:
>>#red, #green or #blue. I would like to use radio buttons to change the
>>value of the instance var, but I don't understand how to do this since
>>the radio button expects to be coupled to a boolean.
>>
>
> It's a slightly roundabout procedure but the easiest way is to let the
> buttons look after themselves (with a little help from Windows) and just
> hook onto the #valueChanged event for all of the RadioButtoms you add. When
> any of the buttons trigger the event, to say it has changed, you scan
> through them all and locate the one that is selected. Roughly ...
>
> createComponents
> ...
>     redRB := self add: BooleanPresenter new name: 'red'.
>     blueRB := self add: BooleanPresenter new name: 'blue'.
>     greenRB := self add: BooleanPresenter new name: 'green.
>
> createSchematicWiring
> ...
>     (Array with: redRB with: blueRB with: greenRB) do: [:each |
>         each when: #valueChanged send: #onRBValueChanged to: self]
>
> onRBValueChanged
>     | newSelection |
>     (Array with: redRB with: blueRB with: greenRB) do: [:each |
>         each value ifTrue: [newSelection := each name]].
>     newSelection = currentRBSelection
>         ifFalse: [
>             currentRBSelection := newSelection.
>             myModel colour: currentRBSelection].
>
> The last bit is needed as both the button being cleared and the button being
> selected trigger the initial #valueChanged event and you probably only want
> to see it once. You could obviously get the same effect by doing something
> similar in your model and losing the #currentRBSelection instVar.
>
> Just in case you weren't aware - you must remember that all the RadioButtons
> that you want to exhibit a group behaviour (when one is selected all the
> others are unselected) must be placed within a single Dolphin ContainerView.
>
> -~-~-~-~-
>
> A simpler alternative, but which I would only recommend for a very small
> number of RadioButtons, it to do the above but give each button it's own
> event/method in #createSchematicWiring. You then end up with lots of methods
> like
>
> onRedRBValueChanged
>     redRB value ifTrue: [myModel colour: #red]
>
> -~-~-~-~-
>
> Both the above can get a bit messy if you have lots of buttons or multiple
> groups so I created a goodie (cue groans from the back of the room) which is
> available on my web site and which helps with the RadioButton management. It
> provides a new Container, RadioButtonGroup, which looks after all the
> RadioButtons placed on it and provides a single event, also passing the name
> of the selected button, to let you know when the selection has changed.
>
> Regards
>     Ian
>
> http://www.iandb.org.uk
>
>
>