Re: [boost] Interest in dimension/unit-checking library?

From: Andy Little (andy_at_[hidden])
Date: 2005-10-21 05:55:52

"Phil Richards" wrote

> I certainly don't disagree with that statement.  But I only really have
> experience of dimensions and units that are compatible with the SI
> view of things, so it is practically impossible to design a library to
> support other modes without knowing more about how they operate...
> (That, I suspect, is true for all the people who've tried over the last
> couple of years.)

Not sure if youre  include me in that. I believe that pqs is a great  solution 
for SI quantities. The primary purpose of a physical quantity library is to 
cater for common practise, rather than being some sort of tool kit for ad-hoc 
unit systems to be created. Defining a unit system is a non-trivial task. The 
dimensional analysis part is trivial really. The difficult part is output and to 
be honest I havent seen a library apart form pqs that tackles this well. Output 
is messy even in the SI.  I believe that users ( including myself) want 
simplicity. I dont want to have to spend time creating output facilities or 
making complex typedefs for commonly used SI quantities. The design of an SI 
quantity library is possible because they have published detailed definitions of 
their base units and  the output format.  pqs doesnt preclude anyone using the 
library for their own system, writing their own unit conversions and their own 
output format. but obviously it cant do that for them, unless some detailed 
definition of what these systems are is provided. Even then is there a common 
requirement there?

regards
Andy Little