Unveiling Design Patterns: A Visual Guide with UML Diagrams

Unveiling Design Patterns: A Visual Guide with UML Diagrams

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  +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
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  Facade Complex system Adapter Type: Structural Whatit 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..