Unveiling Design Patterns: A Visual Guide with UML Diagrams
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The document provides an overview of various behavioral, structural, and creational design patterns in object-oriented software development. It summarizes the functionality and purpose of multiple design patterns such as Visitor, Strategy, Observer, Memento, Factory Method, Singleton, and more. Each pattern is described with its key components and the problems it aims to solve in software architecture.
Unveiling Design Patterns: A Visual Guide with UML Diagrams
- 1. +visitElementA(in a : ConcreteElementA) +visitElementB(in b : ConcreteElementB) «interface» Visitor +visitElementA(in a : ConcreteElementA) +visitElementB(in b : ConcreteElementB) ConcreteVisitor +accept(in v : Visitor) «interface» Element +accept(in v : Visitor) ConcreteElementA +accept(in v : Visitor) ConcreteElementB Client Visitor Type: Behavioral What it is: Represent an operation to be performed on the elements of an object structure. Lets you define a new operation without changing the classes of the elements on which it operates. +templateMethod() #subMethod() AbstractClass +subMethod() ConcreteClass Template Method Type: Behavioral What it is: Define the skeleton of an algorithm in an operation, deferring some steps to subclasses. Lets subclasses redefine certain steps of an algorithm without changing the algorithm's structure. +execute() ConcreteStrategyB +execute() «interface» Strategy Context +execute() ConcreteStrategyA Strategy Type: Behavioral What it is: Define a family of algorithms, encapsulate each one, and make them interchangeable. Lets the algorithm vary independently from clients that use it. +handle() ConcreteState1 +handle() «interface» State +request() Context +handle() ConcreteState2 State Type: Behavioral What it is: Allow an object to alter its behavior when its internal state changes. The object will appear to change its class. -subjectState ConcreteSubject +update() -observerState ConcreteObserver +update() «interface» Observer notifies observes +attach(in o : Observer) +detach(in o : Observer) +notify() «interface» Subject Observer Type: Behavioral What it is: Define a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically. -state Memento +setMemento(in m : Memento) +createMemento() -state Originator Caretaker Memento Type: Behavioral What it is: Without violating encapsulation, capture and externalize an object's internal state so that the object can be restored to this state later. Abstract Factory C Adapter S Bridge S Builder C Chain of Responsibility B Command B Composite S Decorator S Facade S Factory Method C Flyweight S Interpreter B Iterator B Mediator B Memento B Prototype C Proxy S Observer B Singleton C State B Strategy B Template Method B Visitor B Chain of Responsibility +handleRequest() «interface» Handler +handleRequest() ConcreteHandler1 +handleRequest() ConcreteHandler2 Client successor Type: Behavioral What it is: 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. +execute() ConcreteCommand Client +action() Receiver Invoker Command Type: Behavioral What it is: Encapsulate a request as an object, thereby letting you parameterize clients with different requests, queue or log requests, and support undoable operations. +interpret() «interface» AbstractExpression +interpret() : Context TerminalExpression Client Context +interpret() : Context NonterminalExpression Interpreter Type: Behavioral What it is: Given a language, define a representation for its grammar along with an interpreter that uses the representation to interpret sentences in the language. +createIterator() «interface» Aggregate +createIterator() : Context ConcreteAggregate +next() «interface» Iterator +next() : Context ConcreteIterator Iterator Type: Behavioral What it is: Provide a way to access the elements of an aggregate object sequentially without exposing its underlying representation. Client Mediator ConcreteMediator ConcreteColleague «interface» Colleague informs updates Mediator Type: Behavioral What it is: Define an object that encapsulates how a set of objects interact. Promotes loose coupling by keeping objects from referring to each other explicitly and it lets you vary their interactions independently. Copyright © 2007 Jason S. McDonald http://www.McDonaldLand.info Gamma, Erich; Helm, Richard; Johnson, Ralph; Vlissides, John (1995). Design Patterns: Elements of Reusable Object-Oriented Software. Reading, Massachusetts: Addison Wesley Longman, Inc.. +execute() Command
- 2. Facade Complex system Adapter Type: Structural What it is: Convert the interface of a class into another interface clients expect. Lets classes work together that couldn't otherwise because of incompatible interfaces. +adaptedOperation() Adaptee +operation() «interface» Adapter +operation() -adaptee ConcreteAdapter Client +operationImpl() «interface» Implementor +operation() Abstraction +operationImpl() ConcreteImplementorA +operationImpl() ConcreteImplementorB Bridge Type: Structural What it is: Decouple an abstraction from its implementation so that the two can vary independently. +operation() Leaf +operation() +add(in c : Composite) +remove(in c : Composite) +getChild(in i : int) Composite +operation() +add(in c : Composite) +remove(in c : Composite) +getChild(in i : int) «interface» Component children Composite Type: Structural What it is: Compose objects into tree structures to represent part-whole hierarchies. Lets clients treat individual objects and compositions of objects uniformly. +operation() ConcreteComponent +operation() Decorator +operation() «interface» Component +operation() +addedBehavior() -addedState ConcreteDecorator Decorator Type: Structural What it is: Attach additional responsibilities to an object dynamically. Provide a flexible alternative to sub-classing for extending functionality. Facade Type: Structural What it is: Provide a unified interface to a set of interfaces in a subsystem. Defines a high- level interface that makes the subsystem easier to use. Flyweight Type: Structural What it is: Use sharing to support large numbers of fine grained objects efficiently. +request() RealSubject +request() Proxy +request() «interface» Subject Client represents Proxy Type: Structural What it is: Provide a surrogate or placeholder for another object to control access to it. +static instance() +SingletonOperation() -static uniqueInstance -singletonData Singleton Singleton Type: Creational What it is: Ensure a class only has one instance and provide a global point of access to it. +clone() ConcretePrototype2 +clone() «interface» Prototype Client +clone() ConcretePrototype1 Prototype Type: Creational What it is: Specify the kinds of objects to create using a prototypical instance, and create new objects by copying this prototype. «interface» Product ConcreteProduct +factoryMethod() ConcreteCreator +factoryMethod() +anOperation() Creator Factory Method Type: Creational What it is: Define an interface for creating an object, but let subclasses decide which class to instantiate. Lets a class defer instantiation to subclasses. +buildPart() «interface» Builder +buildPart() +getResult() ConcreteBuilder +construct() Director Builder Type: Creational What it is: Separate the construction of a complex object from its representing so that the same construction process can create different representations. «interface» AbstractProduct ConcreteProduct +createProductA() +createProductB() «interface» AbstractFactory +createProductA() +createProductB() ConcreteFactory Client Abstract Factory Type: Creational What it is: Provides an interface for creating families of related or dependent objects without specifying their concrete class. +operation(in extrinsicState) -intrinsicState ConcreteFlyweight +operation(in extrinsicState) -allState UnsharedConcreteFlyweight +operation(in extrinsicState) «interface» Flyweight +getFlyweight(in key) FlyweightFactory Client Copyright © 2007 Jason S. McDonald http://www.McDonaldLand.info Gamma, Erich; Helm, Richard; Johnson, Ralph; Vlissides, John (1995). Design Patterns: Elements of Reusable Object-Oriented Software. Reading, Massachusetts: Addison Wesley Longman, Inc..