Decorator Pattern

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Decorator Pattern

Intent

• The intent of this pattern is to add additional responsibilities dynamically to an object.

Implementation

The figure below shows a UML class diagram for the Decorator Pattern:

 The participants classes in the decorator pattern are:

• Component - Interface for objects that can have responsibilities added to them dynamically.
• ConcreteComponent - Defines an object to which additional responsibilities can be added.
• Decorator - Maintains a reference to a Component object and defines an interface that conforms to Component's interface.
• Concrete Decorators - Concrete Decorators extend the functionality of the component by adding state or adding behavior.

Description

The decorator pattern applies when there is a need to dynamically add as well as remove responsibilities to a class, and when subclassing would be impossible due to the large number of subclasses that could result.

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