[boost] Re: Math Constants Formal Review

From: Gennaro Prota (gennaro_prota_at_[hidden])
Date: 2003-06-07 06:32:27

On Sat, 7 Jun 2003 10:33:20 +0100, "Paul A Bristow"
<boost_at_[hidden]> wrote:

>None of the material is yet ready for inclusion in Boost,
>(with the possible exception of the C Macro values).
>
>What I would like to get is agreement on the presentation of constants.

You mean macros vs. constant variables vs. inline functions? This is
another thing I didn't understand by looking at the documentation: the
FAQ section seems sometimes to imply you have already done a choice in
this regard; for instance:

 Q. Why not use floating-point hardware constants?
 A. Because only a few are available, they are often not the right
    size, are not available on all processors, and most important
    are sometimes not accurate enough.

but then, in another point:

 Q. Why are functions like double pi() which return constants
    provided?
 A. It provides a framework whereby users can plug in special
    implementation and hardware-specific versions

Before that, there's even another answer:

"Because some compilers may be able to produce smaller and/or faster
code.(For example, note that MSVC 7 Standard edition only inlines
"__inline", so this will produce slower and longer code)."

Maybe you meant: "because some compilers generate better code with a
manifest constant and others better code with a function"? I agree
with Daniel that the material need some cleanups if you want us to
understand it.

Genny.