This article includes a list of references, related reading, or external links, but its sources remain unclear because it lacks inline citations. Please help improve this article by introducing more precise citations.(December 2012) (Learn how and when to remove this message)
In object-oriented programming, the command pattern is a behavioral design pattern in which an object is used to encapsulate all information needed to perform an action or trigger an event at a later time. This information includes the method name, the object that owns the method and values for the method parameters.
Four terms always associated with the command pattern are command, receiver, invoker and client. A command object knows about receiver and invokes a method of the receiver. Values for parameters of the receiver method are stored in the command. The receiver object to execute these methods is also stored in the command object by aggregation. The receiver then does the work when the execute() method in command is called. An invoker object knows how to execute a command, and optionally does bookkeeping about the command execution. The invoker does not know anything about a concrete command, it knows only about the command interface. Invoker object(s), command objects and receiver objects are held by a client object, the client decides which receiver objects it assigns to the command objects, and which commands it assigns to the invoker. The client decides which commands to execute at which points. To execute a command, it passes the command object to the invoker object.
Using command objects makes it easier to construct general components that need to delegate, sequence or execute method calls at a time of their choosing without the need to know the class of the method or the method parameters. Using an invoker object allows bookkeeping about command executions to be conveniently performed, as well as implementing different modes for commands, which are managed by the invoker object, without the need for the client to be aware of the existence of bookkeeping or modes.
The central ideas of this design pattern closely mirror the semantics of first-class functions and higher-order functions in functional programming languages. Specifically, the invoker object is a higher-order function of which the command object is a first-class argument.
In object-oriented programming, the commandpattern is a behavioral design pattern in which an object is used to encapsulate all information needed to...
Chain-of-responsibility patternCommand objects are handled or passed on to other objects by logic-containing processing objects CommandpatternCommand objects encapsulate...
through different patterns. The most common patterns are commandpattern and memento pattern. The commandpattern is a software design pattern which encapsulates...
keyboards Commandpattern, a software design pattern in which objects represent actions Voice command, in speech recognition Military command (instruction)...
few sed commands to hold and accumulate text between cycles. sed's command language has only two variables (the "hold space" and the "pattern space")...
MultiCam is a camouflage pattern designed for use in a wide range of environments and conditions which was specifically developed and is produced by American...
The Universal Camouflage Pattern (UCP) is a digital military camouflage pattern formerly used by the United States Army in their Army Combat Uniform. Technicians...
In software engineering, a design pattern describes a relatively small, well-defined aspect (i.e. functionality) of a computer program in terms of how...
In software engineering, the active record pattern is an architectural pattern. It is found in software that stores in-memory object data in relational...
removing decorators on command (like a button press) is a common UI pattern, often implemented along with the Command design pattern. For example, a text...
In computer science, a command queue is a queue for enabling the delay of command execution, either in order of priority, on a first-in first-out basis...
'$0 ~ pattern { print FILENAME ":" $0 }' "pattern=$pattern" "$@" Or You can use the -v var=value command line option (e.g. awk -v pattern="$pattern" .....
Operational Camouflage Pattern (OCP), originally codenamed Scorpion W2, is a military camouflage pattern adopted in 2015 by the United States Army for...
The Incident Command System (ICS) is a standardized approach to the command, control, and coordination of emergency response providing a common hierarchy...
hash function is termed as cleaning, which is implemented through commandpattern by encapsulating the operations such as A d d ( k e y ) {\displaystyle...
Design Patterns: Elements of Reusable Object-Oriented Software (1994) is a software engineering book describing software design patterns. The book was...
ABAB rhyming scheme, from "To Anthea, who may Command him Anything", by Robert Herrick: These rhyme patterns have various effects, and can be used to: Control...
responsibility of dispatching, new commands may be added without changes needed to the code. The front controller pattern may incur performance issues because...
Global Information