Composition involves using recursion to abstract the super-class. It means everything can be treated as a Component and recursion over the structure is “elegantly” handled by polymorphism.
Benefits:
- Can be used to represent a tree data structure.
- Allows treating complex and simple objects in homogeneous manner.
Disadvantages:
- Assumes there is a reasonably homogeneous interface for all elements of the graph, we don’t know where exactly to put operations for adding, removing and accessing children.
- Recursive operations are distributed all over the class hierarchy. Can make understanding more difficult and can make extension more difficult.