Design Patterns: Elements of Reusable Object-Oriented Systems


By: E. Gamma, R. Helm, R. Johnson, J. Vlissides
Published in: Addison-Wesley, 1995

Summary: Describes simple and elegant solutions to problems in object-oriented design.

Pattern: Abstract Factory

Pages: 87-95

Provide an interface for creating families of related or dependent objects without specifying their concrete classes.

Category: Creational

Pattern: Builder

Pages: 97-106

Separate construction of a complex object from its representation so that the same construction process can create different representations.

Category: Creational

Pattern: Factory Method

Pages: 107-116

Define an interface for creating an object, but let subclasses decide which class to instantiate. This allows a class to defer instantiation to subclasses.


Category: Creational

Pattern: Prototype

Pages: 117-126

Specify the kinds of objects to create using a prototypical instance, and create objects by copying this prototype.

Category: Creational

Pattern: Singleton

Pages: 127-134

Ensure a class only has one instance, and provide a global point of access to it.

Category: Creational

Pattern: Adapter

Pages: 139-150

Convert the interface of a class to one expected by clients. This lets classes work together that couldn't otherwise because of incompatible interfaces.

Category: Structural

Pattern: Bridge

Pages: 151-161

Decouple an abstraction from its implementation so the two can vary independently.

Category: Structural

Pattern: Composite

Pages: 163-173

Compose objects into tree structures to represent part-whole hierarchies. Clients can then treat individual objects and compositions of objects uniformly.

Category: Structural

Pattern: Decorator

Pages: 175-184

Attach additional responsibilities to an object dynamically. This provides a flexible alternative to subclassing for extending functionality.

Category: Structural

Pattern: Facade

Pages: 185-193

Provide a unified interface to a set of interfaces in a subsystem. A facade defines a higher-level interface that makes the subsystem easier to use.

Category: Structural

Pattern: Flyweight

Pages: 195-206

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

Category: Structural

Pattern: Proxy

Pages: 207-217

Provide a surrogate or placeholder for another object.

Category: Structural

Pattern: Chain of Responsibility

Pages: 223-232

Avoid coupling the sender of a request to its receiver by giving more than one object a chance to handle the request. Chain the receiving objects and pass the request along the chain until an object handles it.

Category: Behavioral

Pattern: Command

Pages: 233-242

Encapsulate a request as an object, allowing the parameterization of clients with different requests, queue or log requests, and support undoable operations.

Category: Behavioral

Pattern: Interpreter

Pages: 243-255

Given a language, define a representation for its grammar along with an interpreter that uses the representation to interpret sentences in the language.

Category: Behavioral

Pattern: Iterator

Pages: 257-271

Provide a way to access the elements of an aggregate object sequentially without exposing its underlying representation.

Category: Behavioral

Pattern: Mediator

Pages: 273-282

Define an object that encapsulates how a set of objects interact. Promote loose coupling by keeping objects from referring to each other explicitly.

Category: Behavioral

Pattern: Memento

Pages: 283-291

Without violating encapsulation, capture and externalize an object's internal state so the object can be restored to the state.

Category: Behavioral

Pattern: Observer

Pages: 293-303

Define a one-to-many dependency between objects so that when one object changes state, the others are notified and updated automatically.

Category: Behavioral

Pattern: State

Pages: 305-313

Allow an object to alter its behavior when its internal state changes. The object will appear to change its class.

Category: Behavioral, Finite State Machines

Pattern: Strategy

Pages: 315-323

Define a family of algorithms, encapsulate each one, and make them interchangeable. Strategy lets the algorithm vary independently from clients that use it.

Category: Behavioral

Pattern: Template Method

Pages: 325-330

Define the skeleton of an algorithm, deferring some steps to subclasses. This allows subclasses to redefine certain steps of an algorithm without changing the algorithm's structure.

Category: Behavioral

Pattern: Hook Method

Pages: 328

Contains: Hook Method [Pree94],

Pattern: Visitor

Pages: 331-344

Represent an operation to be performed on the elements of an object structure, letting you define a new operation without changing the classes of the elements on which it operates.

Category: Behavioral