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From: Ian0Kerr@my-deja.com (Ian)
Newsgroups: comp.lang.ada
Subject: Re: Dimensions (was Re: Another Idea for Ada 20XX)
Date: 10 Dec 2001 06:09:29 -0800
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"Mark Lundquist" <mlundquist2@attbi.com> wrote in message news:<7KbQ7.13821$L51.28784@rwcrnsc54

> But the worst is still to come :-).  These schemes are quite brittle and
> unscalable, because:
> 
> (d) you have to define all your visibly quasi-numeric operations on every
> combination of types for base and derived units, so you have a
> multiplicative explosion on your hands

Not if you define each only in terms of the nearest suitable type and
chain the conversions between them. Then you only have an O(N)
expansion where N is the number of unit types. If at compile time a
table is constructed with the conversions used in any builds then thes
will not be large in number.

E.g. 1 yard is 3 feet which is 3*12 inches which is 3*12*0.00254
metres.

I don't see any unsurmountable problem.

> (e) the explosion continues if you want more than one unit per dimension.
> It explodes in both new overloadings of the quasi-numeric operations, and
> also in the unit conversions.

See above. No explosion.
 
> Mark

Ian