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Aggregation vs Composition

 
Greenhorn
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What is the difference between aggregation and composition?
 
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Composition is really a strong form of aggregation.
  • Composed objects have only one owner
  • Composed objects cannot exist independent of their owner (components live and die with their owner)
  • Aggregations may form "part of" the aggregate, but may not be essential to it. They also may also exist independent of the aggregate.


  • [ May 30, 2003: Message edited by: Lasse Koskela ]
     
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    With other words: Composition adds a responsibility for controlling the lifetime of the part.
    In garbage collected languages like Java, there isn't much use for composition, in fact...
     
    Consider Paul's rocket mass heater.
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