Structural Patterns

Structural design patterns explain how to assemble objects and classes into larger structures while keeping these structures flexible and efficient.

The Patterns

Convert the interface of a class into another interface clients expect

Decouple an abstraction from its implementation so both can vary independently

Compose objects into tree structures to represent part-whole hierarchies

Attach additional responsibilities to an object dynamically

Provide a unified interface to a set of interfaces in a subsystem

Use sharing to support large numbers of fine-grained objects efficiently

Provide a surrogate or placeholder for another object to control access

Pattern	Intent	Complexity	Frequency
Adapter	Make incompatible interfaces work together	⭐⭐	Very Common
Bridge	Separate abstraction from implementation	⭐⭐⭐	Common
Composite	Compose objects into trees	⭐⭐	Common
Decorator	Add responsibilities dynamically	⭐⭐	Common
Facade	Simplify complex subsystems	⭐	Very Common
Flyweight	Share common state efficiently	⭐⭐⭐	Less Common
Proxy	Control access to objects	⭐⭐	Common