Object Oriented Software - Midterm

36 Design Patterns and their descriptions + code

Simple Factory

Is a creational design pattern that features a class that has one creation method with a large conditional that’s based on method parameters chooses which product class to instantiate and then return

Abstract Factory

is a creational design pattern that lets you produce families of related objects without specifying their concrete classes. (Factories of Factories)

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 an object that will be created. 

Prototype

Is a creational design pattern that lets you copy/clone existing objects without making your code dependent on their classes.

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. 

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. 

Adapter

Is a structural design pattern that allows objects with incompatible interfaces to collaborate. 

Bridge

Is a structural design pattern that lets you split/seperate a large class or set of closely related classes into two separate hierarchies, abstraction and implementation, which can be developed independently of each other. 

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.

Facade

Is a structural design pattern that provides a simplified interface to a library, a framework, or any other complex set of classes.

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 in each object.

Object Pool

Is a structural design pattern that can offer a significant performance boost, it is the most effective in situations where the cost of initializing a class is high and the number of instantiations in use at any one time is relatively low

Stategy

Is a behavioural 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

Is a behavourial 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.

Observer

Is a behavioural design pattern that lets you define a subscription mechanism to notify multiple objects about any events that happen to the objects they’re observing

Iterator

Is a behavioural design pattern that lets you traverse elements of a collection without exposing its underlying representation (list, stack, tree, etc).

Command

Is a behavioural design pattern that turns a request into a standalone 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.

Mediator

Is a behavioural 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.

Visitor

Is a behavioural design pattern that lets you separate algorithms from the objects on which they operate.

Proxy

Is a (behavioural) design pattern that lets you provide a substitute or placeholder for another object. This design pattern controls access to the original object, allowing you to perform something either before or after the request gets through to the original object.

Memento

Is a behavioural design pattern that lets you save and restore the previous state of an object without revealing the details of its implementation.

Interpretor

Is a behavioural design pattern that maps the domain to a language, the language to a grammar, and the grammar to a hierarchical object. 

Chain of Responsibility

Is a behavioural 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. 

State

Is a behavioural design pattern that lets an object alter its behaviour when its internal state changes. It appears as if the object changed its class.

MVC (Model-View-Controller)

A compound pattern that seperates an application into three distinct components: the model, the view, and the controller(s).

Null Object

Is a behavioural design pattern that encapsulates the absence of an object (by providing a substitutable alternative that offers suitable default “do nothing“ behaviour).

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.