Behavioral pattern: Difference between revisions

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{{short description|Type of software design pattern}}

In [[software engineering]], '''behavioral design patterns''' are [[design pattern (computer science)|design pattern]]s that identify common communication patterns betweenamong objects and realize these patterns. By doing so, these patterns increase flexibility in carrying out this communication.

== Design patterns ==

Examples of this type of design pattern include:

* ;[[Chain ofBlackboard responsibilitydesign pattern]]

: Provides a computational framework for the design and implementation of systems that integrate large and diverse specialized modules, and implement complex, non-deterministic control strategies

* [[Command pattern]]

;[[Chain-of-responsibility pattern]]

* [[Event listener]]

: Command objects are handled or passed on to other objects by logic-containing processing objects

* [[Interpreter pattern]]

* ;[[IteratorCommand pattern]]

: Command objects encapsulate an action and its parameters

* [[Mediator pattern]]

;"Externalize the stack"

* [[Memento pattern]]

: Turn a [[Recursion (computer science)|recursive function]] into an [[iterative function]] that uses a [[call stack|stack]]<ref>{{cite web

* [[Observer pattern]]

|url = http://c2.com/

* [[State pattern]]

|title = Externalize The Stack

* [[Strategy pattern]]

|date = 2010-01-19

* [[Template method pattern]]

|publisher = c2.com

* [[Visitor pattern]]

|archive-url = https://web.archive.org/web/20110303085751/http://c2.com/

* [[Single-serving visitor pattern]]

|archive-date = 2011-03-03

* [[Hierarchical visitor pattern]]

|access-date = 2012-05-21

|url-status = bot: unknown

}}</ref>

* ;[[Interpreter pattern]]

: Implement a specialized computer language to rapidly solve a specific set of problems

;[[Iterator pattern]]

: [[Iterator]]s are used to access the elements of an aggregate object sequentially without exposing its underlying representation

* ;[[Mediator pattern]]

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

* ;[[Memento pattern]]

: Provides the ability to restore an object to its previous state (rollback)

;[[Null object pattern]]

: Designed to act as a default value of an object

<dl>

* <dt>[[Observer pattern]] </dt>

<dd>Defines a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically. The variant '''weak reference pattern''' decouples an observer from an observable to avoid memory leaks in environments without automatic weak references.<ref>{{cite web |last=Nakashian |first=Ashod |date=2004-04-11 |title=Weak Reference Pattern |url=http://c2.com/ |url-status=bot: unknown |archive-url=https://web.archive.org/web/20110303085751/http://c2.com/ |archive-date=2011-03-03 |access-date=2012-05-21 |publisher=c2.com}}</ref></dd></dl>

;[[Protocol stack]]

: Communications are handled by multiple layers, which form an encapsulation hierarchy<ref>{{cite web

|url = http://c2.com/

|title = Protocol Stack

|date = 2006-09-05

|publisher = c2.com

|archive-url = https://web.archive.org/web/20110303085751/http://c2.com/

|archive-date = 2011-03-03

|access-date = 2012-05-21

|url-status = bot: unknown

}}</ref>

;[[Publish–subscribe pattern]]<dd>A messaging pattern where senders (publishers) and receivers (subscribers) are decoupled via message topics and brokers. Commonly used in distributed systems, this pattern supports asynchronous, many-to-many communication.</dd>

;[[Scheduled-task pattern]]

: A task is scheduled to be performed at a particular interval or clock time (used in [[real-time computing]])

* ;[[Single-serving visitor pattern]]

: Optimise the implementation of a visitor that is allocated, used only once, and then deleted

;[[Specification pattern]]

: Recombinable [[business logic]] in a [[boolean algebra|boolean]] fashion

* ;[[State pattern]]

: A clean way for an object to partially change its type at runtime

* ;[[Strategy pattern]]

: Algorithms can be selected on the fly, using composition

* ;[[Template method pattern]]

: Describes the [[program skeleton|skeleton]] of a program; algorithms can be selected on the fly, using [[Inheritance (object-oriented programming)|inheritance]]

* ;[[Visitor pattern]]

: A way to separate an algorithm from an object

==See also==

* [[Hierarchical visitorConcurrency pattern]]

* [[Structural pattern]]

* [[Creational pattern]]

* [[CommandStructural pattern]]

==References==

{{Reflist}}

{{Design Patterns patterns}}

{{comp-sci-stub}}

[[Category:Software design patterns]]