Design Pattern Decision TreeDPDT

Design Pattern Catalog

Compare Patterns

Creational

Creation logic is getting complex or scattered

Singleton

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

Builder

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

Prototype

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

Abstract Factory

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

Factory Method

Define an interface for creating an object, but let subclasses decide which class to instantiate. Factory Method lets a class defer instantiation to subclasses.

Structural

Fighting component boundaries or external dependencies

Adapter

Convert the interface of a class into another interface clients expect, enabling classes to work together that otherwise could not due to incompatible interfaces.

Facade

Provide a unified, simplified interface to a set of interfaces in a subsystem, making the subsystem easier to use.

Decorator

Attach additional responsibilities to an object dynamically, providing a flexible alternative to subclassing for extending functionality.

Proxy

Provide a surrogate or placeholder for another object to control access to it.

Composite

Compose objects into tree structures to represent part-whole hierarchies, letting clients treat individual objects and compositions uniformly.

Bridge

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

Behavioral

Behavior keeps changing, conditionals keep growing

Observer

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

Strategy

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

State

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

Command

Encapsulate a request as an object, thereby letting you parameterize clients with different requests, queue or log requests, and support undoable operations.

Chain of Responsibility

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.

Template Method

Define the skeleton of an algorithm in a method, deferring some steps to subclasses. Template Method lets subclasses redefine certain steps of an algorithm without changing the algorithm's structure.