Re: [boost] [Review] Quantitative Units library review begins today, March 26

From: Deane Yang (deane_yang_at_[hidden])
Date: 2007-03-26 14:14:00

Zach Laine wrote:
>
> Specifically,
> 
> quantity<force>     F(2.0*newton);
> quantity<length>    dx(2.0*meter);
> F.value() = dx.value();
> 
> is an abomination and should be impossible.  If I really want to do
> this, why not make me go through the constructor, so that attention is
> more obviously called to what I'm doing?  I could also live with using
> a purposely ugly cast here, but since quantity_cast() has some
> perfectly legitimate and safe uses, I would much prefer a different
> syntax that draws attention to this unsafe act, such as
> quantity_reinterpret_cast().

I agree completely with Zach's views on this. It's OK to have a const 
member function .value() but not a mutating one.

> 
> I and a lot of other users badly need support for Imperial units.  As
> it stands now, we will each be required to write nearly identical code
> to do so.  This should be included in the library.
> 

Matthias Schabel wrote:
 >
 > The problem with these non-standard units is that they don't really
 > form a
 > well-defined unit system. ...
 > We have, however, supplied a number of examples of how to
 > roll your own unit system...
 > )

I agree with Zach and also want to be able to define units without 
having to "roll my own unit system".