Design Patter - Command Pattern

Command Pattern

• Purpose
  - Encapsulates a request as an object.
  - This allows the request to be handled in traditionally object based relationships such as queuing and callbacks.
• Use When
  - Requests need to be specified, queued, and executed at variant times or in variant orders.
  - A history of requests is needed.
  - The invoker should be decopupled from the object handling the invocation.

• Every time you want to modify the behavior of a button, you need to touch the client code.
• Encapsulates a request as an object.

 

• We can see that the receive and ivkoker are decoupled.
• This pattern is useful when operating multiple devices with the remote control.

 

 

• Command decouples the object that invokes the operation from the one that knows how to perform it. 
• Commands cand be manipu;lated and extended like any other object.
• You can aeemble commands into a composite command.