31. Composite

• Problem to solve:

  • When dealing with tree-structured data, programmers often have to discriminate between a leaf-node and a branch.

  • This makes code more complex, and therefore, error prone.

• Solution:

  • The solution is an interface that allows treating complex and primitive objects uniformly.

  • The objects are composed into tree structures to represent part-whole hierarchies.

  • Composite lets clients treat both individual objects as well as object compositions uniformly.