Cheatography
https://cheatography.com
Design patterns are formalized best practices that the programmer can use to solve common problems when designing an application or system.
This is a draft cheat sheet. It is a work in progress and is not finished yet.
Creational Patterns
|
Factory Method Provides an interface for creating objects in a superclass, but allows subclasses to alter the type of objects that will be created.
|
|
Abstract Factory Lets you produce families of related objects without specifying their concrete classes.
|
|
Builder Lets you construct complex objects step by step. The pattern allows you to produce different types and representations of an object using the same construction code.
|
|
Prototype Lets you copy existing objects without making your code dependent on their classes.
|
|
Singleton Lets you ensure that a class has only one instance, while providing a global access point to this instance.
|
Creational patterns provide various object creation mechanisms, which increase flexibility and reuse of existing code.
Behavioural Design Patterns
|
Chain of Responsibility Lets you pass requests along a chain of handlers. Upon receiving a request, each handler decides either to process the request or to pass it to the next handler in the chain.
|
|
Command Turns a request into a stand-alone object that contains all information about the request. This transformation lets you pass requests as a method arguments, delay or queue a request's execution, and support undoable operations.
|
|
Iterator Lets you traverse elements of a collection without exposing its underlying representation (list, stack, tree, etc.).
|
|
Mediator Lets you reduce chaotic dependencies between objects. The pattern restricts direct communications between the objects and forces them to collaborate only via a mediator object.
|
|
Momento Lets you save and restore the previous state of an object without revealing the details of its implementation.
|
|
Observer Lets you define a subscription mechanism to notify multiple objects about any events that happen to the object they're observing.
|
|
State Lets an object alter its behaviour when its internal state changes. It appears as if the object changed its class.
|
|
Strategy Lets you define a family of algorithms, put each of them into a separate class, and make their objects interchangeable.
|
|
Template Method Defines the skeleton of an algorithm in the superclass but lets subclasses override specific steps of the algorithm without changing its structure.
|
|
Visitor Lets you separate algorithms from the objects on which they operate.
|
|
|
Structural Design Patterns
|
Adapter Allows objects with incompatible interfaces to collaborate.
|
|
Bridge Lets you split a large class or a set of closely related classes into two separate hierarchies—abstraction and implementation—which can be developed independently of each other.
|
|
Composite Lets you compose objects into tree structures and then work with these structures as if they were individual objects.
|
|
Decorator Lets you attach new behaviours to objects by placing these objects inside special wrapper objects that contain the behaviors.
|
|
Facade Provides a simplified interface to a library, a framework, or any other complex set of classes.
|
|
Flyweight Lets you fit more objects into the available amount of RAM by sharing common parts of state between multiple objects instead of keeping all of the data in each object.
|
|
Proxy Lets you provide a substitute or placeholder for another object. A proxy controls access to the original object, allowing you to perform something either before or after the request gets through to the original object.
|
Structural patterns explain how to assemble objects and classes into larger structures while keeping these structures flexible and efficient.
|
