Re: [boost] Boost Units library preview

From: Andy Little (andy_at_[hidden])
Date: 2006-08-29 14:23:17

"Ben Strasser" <strasser.ben_at_[hidden]> wrote in message 
news:loom.20060829T195422-914_at_post.gmane.org...
> Andy Little <andy <at> servocomm.freeserve.co.uk> writes:
>
>> "Ben Strasser" <strasser.ben <at> googlemail.com> wrote in message
>> news:loom.20060829T180704-945 <at> post.gmane.org...
>>
>> > In more complex situations you run accross the
>> > problem that you can no longer
>> > deduce the correct unit type. This is
>> > also the reason why PQU (= Physical
>> > Quantities Units) has introduced annomymous
>> > units. However in what way does this
>> > help? None that I can think of because in both situation (meaning non
>> > printable units and annomymous units) the users
>> > has to indicate how to print the units.
>>
>> FWIW, if this is a statement regarding Quan, then it is incorrect
>
> Then please correct me. Somewhere in this
> same thread you said:
>
>> In the calculation:
>>
>> force * distance;
>>
>> The programmer might be dealing with a
>> force acting at a moment, or the energy
>> required to move an object. There is no
>> way to tell from the calculation which.
>> [...] , so the result is an
>> anonymous quantity.
>>
>> One could apply various rules [...], but as I
>> can't apply a rule easily to the above case,
>> I opted to apply the same rule to every case
>> of  dimensionful multiplication and division,
>> which was to return an anonymous quantity and
>> leave it to the programmer to decide which
>> quantity they were dealing with.
>
> The way I understood this is that the library isn't
> able to deduce what symbol corresponds to the units
> so the user has to make a choice.
>
> Did I misunderstand this or did I only get
> the terminology wrong?

Quan provides a default output format for "anonymous quantities", but apparently 
these  are unnecessary anyway so I really wouldnt about it, but please dont make 
incorrect statements regarding my library. Thankyou.

regards
Andy Little