Re: [boost] Re: Dimensional Analysis Interest?

From: Beman Dawes (bdawes_at_[hidden])
Date: 2003-10-15 09:37:09

In prior discussions of units-of-measure problems, it was pointed out that 
in many applications it might be necessary to tag types with more than just 
simple units-of-measure like gallons or liters.

For example, if x and y are variables representing gallons, it still may 
not be valid to add them together. (Consider that x may be gallons of 
unleaded regular gasoline, while y may be gallons of propane.)

Even if x and y both represent gallons of propane, there can still be 
problems: to do addition correctly, you must either know that the gallons 
are temperature compensated or know the temperature of each. (Propane's 
coefficient of expansion is high enough that by US law commercial 
measurements must be temperature compensated.)

IIRC, prior discussions leaned toward solving such problems by allowing for 
user supplied units-of-measure. That would allow industry specific problems 
like the above examples to be solved without requiring the library to know 
about every unit-of-measure need in the world.

--Beman