Also known as
Attach additional responsibilities to an object dynamically. Decorators provide a flexible alternative to subclassing for extending functionality.
- To add responsibilities to individual objects dynamically and transparently, that is, without affecting other objects
- For responsibilities that can be withdrawn
- When extension by subclassing is impractical. Sometimes a large number of independent extensions are possible and would produce an explosion of subclasses to support every combination. Or a class definition may be hidden or otherwise unavailable for subclassing
Real world examples
- java.io.InputStream, java.io.OutputStream, java.io.Reader and java.io.Writer