Pattern Catalog

Creational Patterns

Pattern	Purpose	Key Benefit
Factory	Create objects without specifying exact class	Encapsulates object creation logic
Singleton	Ensure only one instance exists	Controlled access to single instance
Builder	Construct complex objects step by step	Separates construction from representation
Prototype	Clone objects instead of creating new ones	Avoids expensive initialization
Abstract Factory	Create families of related objects	Ensures product compatibility

Behavioral Patterns

Pattern	Purpose	Key Benefit
Strategy	Define interchangeable algorithm families	Runtime algorithm selection
Observer	Notify dependents of state changes	Loose coupling between objects
Command	Encapsulate requests as objects	Parameterize and queue operations
Chain of Responsibility	Pass requests along handler chain	Decouples sender from receiver
Interpreter	Interpret language grammar	Represents grammar rules as classes
State	Alter behavior when internal state changes	State-specific behavior encapsulation
Template Method	Define algorithm skeleton in base class	Subclasses override specific steps
Iterator	Access elements sequentially	Uniform traversal interface
Visitor	Separate algorithms from object structure	Add operations without modifying classes
Mediator	Reduce coupling between communicating objects	Centralized communication
Memento	Capture and restore object state	Externalized state management

Structural Patterns

Pattern	Purpose	Key Benefit
Decorator	Add responsibilities dynamically	Flexible alternative to subclassing
Adapter	Make incompatible interfaces work together	Interface compatibility
Composite	Treat individual and composed objects uniformly	Tree structure representation
Facade	Provide simplified interface to complex subsystem	Reduces system complexity
Proxy	Control access to another object	Lazy initialization, access control
Bridge	Decouple abstraction from implementation	Independent variation of abstractions