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From: Paul A Bristow (boost_at_[hidden])
Date: 2004-03-07 11:08:17

Sorry to bang on about this, but we still haven't sorted it out.

To re-cap, it seems that the solution proposed a long time ago by
Michael Kenniston and recently by Thorsten Ottosen don't give as much
'extendibility' to user defined floating point types (quaddoubles,
RWsuper doubles, rational, interval, etc) as some would like.

Daniel Frey has produced two solutions which seem to provide this


1 His version 2 works on Intel (EDG?) and GCC compilers, but trips VC7.1
(see below).

Is this because VC7.1 is 'broken', or is it because it isn't really
legal code (or is the language ill-defined in this area).

Opinions on this would be most welcome. What the other compilers make of
his code may be revelevant?

If there is a consensus that VC is wrong, then we can perhaps get it

2 Daniel's Version 3 uses typeof which is not yet part of the language
- but is very likely to become so eventually.

Our other option is to wait until it is added before we try to provide
the ultimate 'constants' solution.


Paul A Bristow
Prizet Farmhouse, Kendal, Cumbria UK LA8 8AB
+44 1539 561830 +44 7714 330204
mailto: pbristow_at_[hidden]

| -----Original Message-----
| From: boost-bounces_at_[hidden]
| [mailto:boost-bounces_at_[hidden]] On Behalf Of Daniel Frey
| Sent: 01 March 2004 21:40
| To: boost_at_[hidden]
| Subject: [boost] Re: [math constants] C++ Language gurus
| views needed and Codewarrior & Comeau testers
| Phil Richards wrote:
| > On Mon, 01 Mar 2004 18:09:20 +0000, Paul A Bristow wrote:
| > [Daniel Frey said:]
| >
| >>| I really suggest you look at my code at
| >>|
| <| /MathConstants/>,
| which solves
| >>| all of the above points.
| >>Except that VC 7.1 doesn't think it is legal C++ :-((
| >>I think we need to establish if it is correct (as gcc and
| Intel think it
| >>is)
| >
| > Nope, as has been said a number of times, it is not valid
| C++. typeof is
| > not in the existing C++ standard. It is a very useful extension
| > implemented by a number of vendors, but that doesn't make
| it standard.
| That's not fair. VC7.1 is *not* failing because of my use of
| typeof. We
| could provide a fallback for retrieving the return type of the
| expressions. The point is, that the VC7.1 already failed with an
| "Internal compiler failure" on previous version that were
| 100% ISO-C++.
| Please try to understand the problem first before accusing me
| of writing
| offending non-standard code which hurts the poor, innocent VC7.1 :-)

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