Data Model for Quantity v0.5 - inheritance vs aggregation

[Brian Thomas]

On Monday 10 May 2004 04:10 pm, Patrick Dowler wrote:
> FYI - realization is the relationship between an interface and the class that 
> implements it. One interface still inherits from another. the Q document does 
> specify an inheritance relationship.

	Yes, I agree. I was sloppy in my description. Nevertheless, the intention
	is correct, we shouldn't see aggregation lines in the diagram, just 3 or 4
	interfaces inheriting from one another in direct succession. 

> [snip description of how this inheritance relationship between interfaces 
winds up forcing one-to-one implementation anyways]
>
> The interfaces in the Q doc specify a type of relationship that the
> implementations are more or less forced to follow.
>
> Interfaces are meant to be declarative ("I have these methods!") first and
> can - if it is valuable - have an interface heirarchy. Here we have both
> and it is an extra burden and limitation on implementors.

	What is your solution then? Have you been running into problems
	implementing these interfaces?

	=b.t.

-- 

  * Dr. Brian Thomas 

  * Dept of Astronomy/University of Maryland-College Park 
  * Code 630.1/Goddard Space Flight Center-NASA

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