Design Patterns | Cheat Sheet List
A collection containing all Design Pattern Cheat Sheets
Design Patterns are an essential resource and foundational knowledge for every developer — they are very helpful for solving programmatic problems, help with consistent communication with other developers about system design, and are a significant introduction into object composition (besides inheritance) and dependency inversion.
Creational Patterns
Creational Patterns are indispensable when abstracting the instantiation process of objects. The encapsulation of concrete classes and hiding the creational process is highly important.
Factory Method is a creational design pattern that provides an interface for creating objects in a superclass, but allows subclasses to alter the type of objects that will be created.
Abstract Factory
Abstract Factory is a creational design pattern that lets you produce families of related objects without specifying their concrete classes.
Builder
Builder is a creational design pattern that 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
Prototype is a creational design pattern that lets you copy existing objects without conditioning your code on their classes.
Singleton
Singleton is a creational design pattern that lets you ensure that a class has only one instance, while providing a global access point to this instance.
Structural Patterns
Structural Patterns are indispensable when objects are combined to create new functionalities. Comprehensive structures are built by using compositions of classes and objects. This provides flexibility due to a variable composition structure during runtime. One thus achieves an increase in efficiency and consistency.
Adapter
Adapter is a structural design pattern that allows objects with incompatible interfaces to collaborate.
Bridge
Bridge is a structural design pattern that 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.
Composite
Composite is a structural design pattern that lets you compose objects into tree structures and then work with these structures as if they were individual objects.
Decorator
Decorator is a structural design pattern that lets you attach new behaviors to objects by placing these objects inside special wrapper objects that contain the behaviors.
Facade
Facade is a structural design pattern that provides a simplified interface to a library, a framework, or any other complex set of classes.
Flyweight
Flyweight is a structural design pattern that 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 inside each object individually.
Proxy
Proxy is a structural design pattern that 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.
Behavioral Patterns
Behavioral Patterns deal with algorithms and the assignment of responsibilities to objects. Furthermore, they describe mutual communication patterns and grasp complex program sequences. They are, therefore, very well suited in areas where complicated code needs to be made readable and maintainable. Extensions are, in consequence, perfect and quickly implementable.
Chain of Responsibility
Chain of Responsibility is a behavioral design pattern that 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
Command is a behavioral design pattern that turns a request into a stand-alone object that contains all information about the request. This transformation lets you pass requests as method arguments, delay or queue a request’s execution, and support undoable operations.
Iterator
Iterator is a behavioral design pattern that lets you traverse elements of a collection without exposing its underlying representation (list, stack, tree, etc.).
Mediator
Mediator is a behavioral design pattern that 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.
Memento
Memento is a behavioral design pattern that lets you save and restore the previous state of an object without revealing the details of its implementation.
Observer
Observer is a behavioral design pattern that lets you define a subscription mechanism to notify multiple objects about any events that happen to the object they are observing.
State
State is a behavioral design pattern that lets an object alter its behavior when its internal state changes. It appears as if the object changed its class.
Strategy
Strategy is a behavioral design pattern that lets you define a family of algorithms, put each of them into a separate class, and make their objects interchangeable.
Template Method
Template Method is a behavioral design pattern that defines the skeleton of an algorithm in the superclass but lets subclasses override specific steps of the algorithm without changing its structure.
Visitor
Visitor is a behavioral design pattern that lets you separate algorithms from the objects they operate on.
Conclusion
Thanks for reading! Follow me on Medium, Twitter, or Instagram, or subscribe here on Medium to read more about DevOps, Agile & Development Principles, Angular, and other useful stuff. Happy Coding! :)
