[Boost-users] [units]

Subject: [Boost-users] [units]
From: Robert Ramey (ramey_at_[hidden])
Date: 2013-09-15 14:18:12

I have an urgent and definite need for the functionality which boost.units 
is meant to provide.  The concept is quite simple so I had expected it to be 
relatively easy to use. I had anticipated spending a few hours perusing the 
documentation and examples, adding code to my application and moving on. 
T'was not to be. I'm now on day 3 (or 4?) trying to figure this thing out.

The main hurdle is that the documentation is indecipherable.

There are a number of templated classes defined which depend upon each 
other. I expect to find a page for each of the templates along with a 
description of what the template arguments should be.  (Ideally these should 
be backed up with concept checking classes).  Ideally there would be a small 
example showing how one would use these templates.

It seems that the library is layered from low level ideas to higher level 
ones.  The documentation touches on this - but its not really formalized.

Theres a reference section which includes scores of things like base_units 
types for wide variety of units - but no where is there any indication how 
these should be used - not even in the examples are they used.

There is a concept of "system" (of dimensions?) and the idea of mixing units 
from different systems and the idea that the same dimension (eg length) have 
multiple renderings in the system (nautical vs metric).

I realize I've likely got this wrong and I'm not asking for anyone to 
explain this to me here - my point is that what should be very simple is 
incredibly confusing. I still haven't figured out whether it's only the 
documentation which is incomplete or if it is the actual logical design of 
the library itself is what's flawed.  I'm still working on this.

I don't remember much traffic on this list regarding this library and if I 
google information on boost C++ units library I don't get a whole lot of 
hits.  This could mean that that the library is so easy to use no one ever 
needs to ask about it or it could be that almost no one every uses it.  In 
Boost we don't gather statistics on usage by library so I don't which of 
these it might be. So my question is: Has anyone had good success with this 
library?  How much effort did it take? What did you have to do to make it 
work. I would be curious about any other user feed back in these questions.

Robert Ramey