Examining architectural aspects

In the Component hierarchies section, I showed you that component-based UI frameworks rely on specialization. General features and concepts are implemented in the root component or one of its immediate successors. Such general features include the following:

• Location and size on screen
• Basic visual aspects such as background (color)
• Simple user interactions (reacting to clicks)

Any component will provide these features, either in a specialized way or in its basic implementation. Android’s view system is class-based, so changing functionality is done by overriding the methods of the parent.

Composable functions, on the other hand, do not have a shared set of properties. By annotating a function with @Composable, we make certain parts of Jetpack Compose aware of it. But besides not specifying a return type, composables seem to have few things in common. However, this would have been a pretty short-sighted architectural...