[boost] Re: physical quantities (was: runtime unit-modifiable ...)

From: Daniel Frey (daniel.frey_at_[hidden])
Date: 2004-01-07 03:38:05

Reece Dunn wrote:
> Jan Langer wrote:
>> i do not really know what you mean, but 5 * meter(s) looks very 
>> natural to me. a scalar factor 5 is multiplied to a length of a meter, 
>> which results in a length of 5 meters. if you have an implicit 
>> value_type and if you assume to be solely in a specific units system, 
>> the syntax
>>     length l = 5*meters;
>> expresses all facts.

FWIW this is also the syntax I used when I played with a unit library 
some months ago. Hadn't taken the time to go further, though, but it 
seemed a natural syntax to me, too.

>   Speed s = 2 m / s;

This is one of the pitfalls! I haven't found a solution, but I'd like to 
point out that it is a problem which needs to be addressed. Units often 
have very brief identifiers which than clash too easily with the 
variables one usually uses. And you don't want to write

unit::Speed s = 2 * unit::m / unit::s;

all the time, do you? I'm not very constructive, I know... :)

Regards, Daniel

-- 
Daniel Frey
aixigo AG - financial solutions & technology
Schloß-Rahe-Straße 15, 52072 Aachen, Germany
fon: [phone], fax: [phone]
eMail: daniel.frey_at_[hidden], web: http://www.aixigo.de