Relationship between Q and STC - Frames & Mapping

[Martin Hill]

David Berry wrote:

> Brian,
> 
> A Quantity is for
> recording values of some phenomenon and so encapsulates two components:
> 
> 1) the Frame which identifies and describes the phenomenon
> 2) the (Mapping or ValuesList) which provides the values of the phenomenon
> 

Done a bit more thinking (in the pub, oh dear!).

 From what I gather Mapping is not part of what is presented by the 
Quantity interface.  As far as a Quantity user is concerned, we just do 
getValue(), and we get the value back according to the described Frame.
What is done to turn the internal value into the Frame-described value 
is an implementation issue.

In which case please let's get rid of the Mapping from the Quantity 
interface!  In fact it probably doesn't belong in the *model* at all, 
especially as we will need to work out how to map between Quantities 
where we will definitely need a modelled mapping, called, say, Mapping...

Does that sound OK?

-- 
Martin Hill
www.mchill.net
07901 55 24 66