Design Patterns Flashcards
State
Allow an object to alter its behavior when its internal state changes. The object will appear to change its class.
Composite
Compose objects into tree structures to represent part-whole hierarchies. Composite lets clients treat individual and compositions of objects uniformity.
Chain of Responsibility
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.
Adapter
Convert the interface of a class into another interface that clients expect. Adapter lets classes work together that couldn’t otherwise because of incompatible interfaces.
Decorator
Attach additional responsibilities to an object dynamically. Decorators provide a flexible alternative to subclassing for extending functionality.
Flyweight
Use sharing to support large numbers of fine-grained objects efficiently
Facade
Provide a unified interface to a set of interfaces in a subsystem. Facade defines a higher-level interface that makes the subsystem easier to use.
General definition of “Pattern “
A form or model proposed for imitation
Bridge
Decouple an abstraction from its implementation so that the two can vary independently
Abstract Factory
Provide an interface for creating families of related or dependent objects without specifying their concrete classes.
Memento
Without violating encapsulation, capture and externalize an object’s internal state so that the object can be restored to this state later.
Template Method
Define the skeleton of an algorithm in an operation, deferring some steps to subclasses. Template Method lets subclasses define certain steps of an algorithm without changing the algorithm’s structure.
Factory Method
Define an interface for creating an object but let subclasses decide which class to instantiate. Factory Method lets a class defer instantiation to subclasses.
Mediator
Define an object that encapsulates how a set of objects interact. Mediator promotes loose coupling by keeping objects from referring to each other explicitly, and it lets you vary their interaction independently.
Observer
Define a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.
Visitor
Represent an operation to be performed on the elements of an object structure. Visitor lets you define a new operation without changing the classes of the elements on which it operates
Iterator
Access the elements of an aggregate object sequentially without exposing its underlaying representation
Proxy
Provide a surrogate or placeholder for another object to control access to it.
Builder
Separate the construction of a complex object from its representation so that the same construction process can create different representations.
Prototype
Specify the kinds of objects to create using a prototypical instance, and create new objects by copying this prototype.
Strategy
Define a family of algorithms, encapsulate each one, and make them interchangeable. Strategy lets the algorithm vary independently from clients that use it.
Command
Encapsulate a request as an object, thereby letting you parameterize clients with different requests, queue or log requests, and support undoable operations.
Singleton
Ensure a class only has one instance and provide a global point of access to it
