The composite pattern
The composite pattern allows complex tree-like structures to be built from simple components. These components, called composite objects, are able to behave sort of like a container and sort of like a variable depending on whether they have child components. Composite objects are container objects, where the content may actually be another composite object.
Traditionally, each component in a composite object must be either a leaf node (that cannot contain other objects) or a composite node. The key is that both composite and leaf nodes can have the same interface. The UML diagram is very simple:
This simple pattern, however, ...
Get Python: Master the Art of Design Patterns now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.