kevin.hall@motioneng.com wrote:
> I know that with template meta-programming, one can create functions
> that will be evaluated at compile-time.  However, TMP has its
> disadvantages:
>
> (1) Templates do not support floating point numbers
>
> (2) Many compilers will only recurse a certain number of levels (10 to
> 50).  Many useful calculations require possibly hundreds of levels of
> recursion (especially for floating point calculations)
>
> (3) Some experimental work has been done to support floating point
> calculations using templates
> (http://mi.eng.cam.ac.uk/~er258 /code/fp_template.html), but the speed
> is terrible -- FLOPS measuring in the single digits.
>
> Personally, I'd really love to see something provided by the language
> that would allow evaluation of all the functions in <math> at compile
> time.  For example:
>
>     double root_2 =     // user defined variable
>         meta_sqrt(2.0); // compile-time function
>
> What do you guys think?

     You can already write

 const double root_t = sqrt(2.0);

and it will be evaluated during program startup.  You don't
get a compile-time constant, but do you really need one?

    John Nagle
    Animats

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