[boost] [Review] [units]

From: Steven Watanabe (steven_at_[hidden])
Date: 2007-04-04 21:13:05

AMDG

Janek Kozicki wrote:
> My only complaint is about lengthy typenames. Like for example my
> Newton's Law function (attached calculatorform.cpp:65):
>
> quantity<SI::force> newtons_law(const quantity<SI::mass>& m, const
quantity<SI::acceleration>& a) 
> {
>     return m*a;
> }
>   

I don't know of any good general solution.  We have
the identical problem: force is already taken.  It makes
more sense to use it for the unit than the quantity because
you can also have quantity<SI::force, long double>.

> <snip>
>
>
> The "base_unit_converter<>" in Example 16 should be hyperlinked to the
> explanations what it is and how to use it.
>   

I'll make sure that Doxygen finds the definition.

> Documentation should have a FULL list of all predefined units, so it will be a
> quick reference for the users.
>
>   
Ok.
>
> EXAMPLES
>
> Speed "Example 14":
>
> With debug information and no optimizations:
>
> <snip>
>
>
> With units it is faster by two seconds. I ran the test several times, and read
> the code few times. Maybe executable with "slower" units is accidentally better
> synchronized with memory access frequency MHz. Congratulations, you beat me. 
>
> Those results were obtained with:
> gcc version 4.1.2 20061115 (prerelease) (Debian 4.1.1-21)
>   
It's easily within the noise level.

> Yes it should be accepted. Before adding to CVS-HEAD please do following:
>
> 1. support calculations of conversion factors as explained above. Attached file
> calculatorform.cpp:47  (or convince me that I'm wrong, but hey - how to do it
> more conveniently than in this way?)
>   

It should be a compile error.  Try

quantity<SI::dimensionless>(1.0*CGS::dyne/SI::newton)

With the sandbox version

> 2. check for compiler used and emit an #error when unsupported compiler is
> detected. So that users won't waste time on futile fights with their compilers.
>   

Ok.

Thank you for your comments.

In Christ,
Steven Watanabe