May 2018
Beginner
252 pages
6h 19m
English
In Chapter 9, Composing Visual Interfaces, we saw how easy it is to handle events on widgets by attaching actor code blocks. We encountered several examples where a change or action in one face influenced another face—for example, clicking a button changes a text in a field. The text field reacted to the button because we explicitly coded an actor on the button.
Look at the following code snippet:
;-- see Chapter10/reactive1.red:point: [x: 3 y: 5]distance: square-root (point/x ** 2) + (point/y ** 2)print distance ;== 5.8309518948453point/x: 2print distance ;== 5.8309518948453 <-- doesn't change!distance: square-root (point/x ** 2) + (point/y ** 2)print distance ;== 5.385164807134504 <-- changed
The distance word gives ...