Flex, RobotLegs: must you mediate all child components of a visual component?

Question

In the examples for RobotLegs, it appears that mediators are used on every button/textArea, rather than on the custom component that contains these children. This would be very time consuming would it not?

From Joel Hooks InsideRia Example

Dependency injection works better with unambiguous classes. What this means is that by extending TextArea into our new MessageView class, we are creating a specific view component for the dependency injection to act upon. This is important if our application were to have several TextAreas that served different purposes. By dividing up our classes in this way, we are clearly defining the intent of the class and allowing for the dependency injection tools to do their jobs effectively.

Answer 1

No, don't mediate every child component. Your components should be organized into groups that perform related actions. In the examples the components are extremely simple and do not reflect what a real application would look like.

Answer 2

One rule of thumbs I use is thinking if that component needs any communication with the rest of the application, or if its only a part of a whole. Keep in mind that mediator are only intended to serve as a bridge between the view and the app.

For example, if I've a view with a form (asume a login form) I don't mediate all the child components (the textfields, the buttons, etc.) because it would be pointless and would have a proliferation of classes and objects on runtime. When I do the form I think, what does the view by its own? and what the other parts of the app should do with it? When the user fills the form and clicks a button, the view dispatches an event (LoginRequestEvent, for this case), and then the mediator should redispatch that event, making the mediator very lean.

But with practice of the framework, you'll come up with this feel of what you shold mediate. For instance, in one app I mediate every item renderer of a list, and on other I mediate a view stack with two or three navigation contents.

Hope it helps