Composite Pattern

Kind: pattern

Layer: Design Patterns Core

Record: architecture:composite-pattern

Severity: recommended

Scope: structure, tree, hierarchy

Canonical: Ontology

A design pattern that gives leaves and groups one interface, so a tree is traversed without checking which kind each node is.

Listed in Architecture principles, after Decorator Pattern and before Flyweight Pattern.

Requires

• Uniform Component Interface

Reinforces

• Uniform Interface
• Open/Closed Principle (OCP)

Enables

• Recursive Composition
• Leaf/Composite Transparency

Conflicts with

• Leaf-vs-Container Special-Casing

In tension with

• Type Safety

Tensions

• Composite Pattern / Type Safety

Violated by

• Leaf-vs-Container Special-Casing

Severity

• recommended

Category

• Structural Patterns

Linked from

• Contracts / Interfaces / Compatibility
• SOLID / Object-Oriented Design
• Schema / Canonical Data / Semantics
• Structural Patterns
• Severity levels
• The resolutions