Recursive composition

Class diagram :

Strong points :

1. 1. Decoupling and extensibility
   1. 1.1 Maximal factorization of the composition
   2. 1.2 Addition or removal of a leaf does not need code modification
   3. 1.3 Addition or removal of a composite does not need code modification
2. 2. Uniform protocol
   1. 2.1 Uniform protocol on operations of composed object
   2. 2.2 Uniform protocol on composition managing
   3. 2.3 Unique access point for the client class

Spoiled pattern instantiations on different problems

Problem 1 :

Name :

Images composition

Problem wording :

Design a system enabling to draw a graphic image. A graphic image is composed of lines, rectangles, texts and groups. A group may be composed of other groups, lines, rectangles and texts.

Optimal solution :

Static diagram :

This solution allows a good decoupling, and a good extensibility.

Alternative solution :

Static diagram :

Probably the worst solution. No decoupling, no extensibility and none uniform protocol