Design Patterns

creational pattern which defines an interface for creating objects, but delegates the actual responsibility for selecting the class and instantiating the object to a subclass

structural pattern that lets you add responsibilities to an object dynamically

structural pattern that adapts a class with an incompatible interface to fit your needs

behavioral pattern that allows an object to notify other objects when it changes (without knowing what the other objects are)

behavioral pattern that lets subclasses redefine certain steps of an algorithm without changing the algorithm's structure. (Similar to Strategy but allows steps to be changed instead of whole implementation)

behavioral pattern that allows a class to use different variants of an algorithm

creational pattern which defines an interface for creating objects, but delegates the actual responsibility for selecting the class and instantiating the object to a subclass

creational pattern which provides an interface for creating families of related(or dependent) objects without specifying their concrete classes

behavioral pattern that lets subclasses redefine certain steps of an algorithm without changing the algorithm's structure. (Similar to Strategy but allows steps to be changed instead of whole implementation)

creational pattern which provides an interface for creating families of related(or dependent) objects without specifying their concrete classes

structural pattern that lets you add responsibilities to an object dynamically

behavioral pattern that allows a class to use different variants of an algorithm

structural pattern that lets you add responsibilities to an object dynamically

behavioral pattern which encapsulates a request as an object

structural pattern that adapts a class with an incompatible interface to fit your needs

behavioral pattern which encapsulates a request as an object

behavioral pattern that allows a class to use different variants of an algorithm

behavioral pattern that allows an object to notify other objects when it changes (without knowing what the other objects are)

system should be independent of product creation

want to configure with multiple families of products

want to ensure that a product family is used together

when an algorithm consists of varying and invariant parts that must be customized

a class can't anticipate the class of objects it must create

a class can't anticipate the class of objects it must create

a class wants its subclasses to specify the objects it create

you need to use several subclasses, but its impractical to adapt their interfaces by subclassing each one

many classes differ only in their behavior

want to configure with multiple families of products

add responsibilities to individual objects dynamically and transparently

when responsibilities for objects can be withdrawn

when extension of functionality by subclassing is impractical

parameterize objects by an action to perform

client needs different variants of an algorithm

system should be independent of product creation

parameterize objects by an action to perform

specify, queue, and execute requests at different times

structure a system around high-level operations built out of primitives

you want to create a reusable class that cooperates with unrelated classes that might not have compatible interfaces

client needs different variants of an algorithm

system should be independent of product creation

Decouples an abstraction from an implementation so the two can vary independently

Provides a unified interface to a set of interfaces in a subsystem. Facade defines a higher-level interface making the subsystem easier to use.

Provide a surrogate or placeholder for another object to control access to it

Defining an object that encapsulates how a set of objects interact.

A way for controlling communication between classes or entities.

Use sharing to support large numbers of fine-grained objects efficiently

Compose objects into tree structures to represent part-whole hierarchies

Avoid coupling the sender of a request to its receiver by giving more than one object a chance to handle the request

Encapsulate a request as an object, thereby letting you parameterize clients with different requests, queue or log requests, and support undoable operations

Provide a way to access the elements of an aggregate object sequentially without exposing its underlying representation

Define an object that encapsulates how a set of objects interact

Provides a unified interface to a set of interfaces in a subsystem

Converts the interface of a class into another interface clients expect

Attaches additional responsibilities to an object dynamically

Provides a surrogate or placeholder for another object to control access to it

Uses sharing to support large numbers of fine-grained objects efficiently

Specifies the kinds of objects to create using a prototypical instance, and create new objects by copying this prototype

Defines the skeleton of an algorithm in an operation, deferring some steps to subclasses

Represents an operation to be performed on the elements of an object structure

Provides a surrogate or placeholder for another object to control access to it

Has a simulated object that mimics the behavior of a real object in controlled ways1

Specify the kinds of objects to create using a prototypical instance, and create new objects by copying this prototype

Define the skeleton of an algorithm in an operation, deferring some steps to subclasses

Lets you define a new operation without changing the classes of the elements on which it operates

Attach additional responsibilities to an object dynamically

Decouple an abstraction from an implementation so the two can vary independently

Define a family of algorithms, encapsulate each one, and make them interchangeable

Decouples the model from the view, uses data binding from the view to the middle layer, and allows UI/UX designers to work almost independently from application developers

Define a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically

Represent an operation to be performed on the elements of an object structure

Provides an abstract interface to some type of database or other persistence mechanism.

Defines a family of algorithms, encapsulate each one, and make them interchangeable

Compose objects into tree structures to represent part-whole hierarchies