UI Components: Radio buttons
There is no radio button UI component, so how does this work? This example is one possible formulation of how you can build 'compound' components out of collections of UI primitives.
This example uses a ComponentList as a container for a vertical list of rows of radio buttons. The radio buttons themselves are made up of a ComponentGroup that contains a Switch and a Label.
In terms of layouts, all of the above will work with no special wiring, but traditional radio button groups are essentially a series of on/off switches where only one may be in the 'on' state at any one time. How will we replicate that?
The Switch component has a method on it called withAutoToggle, which can change the switch's state based on the reference data. So as usual, what we need to do is store some state (could be anything, just an Int here) in the model, supply the state in the UIContext instance as part of it's reference data (which will be propagated to all components in the hierarchy), and then use that value to auto-toggle the switch.
All that remains is to alter the model state, and we do that by emitting a ChangeValue event onSwitch, picking up the event in the model update, and performing the requested change.
For good measure, we also emit a Log event with a radio button is selected.