Re: [boost] Re: Physical Quantities revisited

From: Phil Richards (news_at_[hidden])
Date: 2003-10-24 11:08:36

On 2003-10-24, Deane Yang <deane_yang_at_[hidden]> wrote:
>  I can't disagree with that, but from listening to the physicists explain 
>  their needs, I haven't heard anything that the physicists want that 
>  isn't also wanted by many of us non-physicists, except the desire to 
>  hardwire the definition of dimensions to actual physical dimensions. So 
>  all I am trying to express is the desire not to have the core library 
>  somehow tied to physical dimensions only.

Why not start with what we know is wanted, and develop from that?

There is clearly a desire for a library which supports
physical dimensions - if at a later point other things are required,
then a bit of refactoring will allow the physical dimension
library to built on the more generic core (if it ever exists).
Much like boost::shared_ptr may, or may not, ever build on a
policy based smart pointer.

>  Angles are indeed difficult to fit within the framework of a 
>  dimensions/units library. The basic problem is that an angle is really a 
>  unitless ratio. [...]

Ahem.  Angles have *lots* of units - degrees, radians, gradians ...
they don't, however, have any "dimensionality".

It is an important, if pedantic, distinction.

phil
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