[boost] Re: Re: Patch for BOOST_STATIC_CONSTANT docs - config-patch.txt

From: Edward Diener (eddielee_at_[hidden])
Date: 2003-01-26 16:25:17

"David Abrahams" <dave_at_[hidden]> wrote in message
news:uu1fvolxp.fsf_at_boost-consulting.com...
>
> Shouldn't we stick the -b- option in our borland toolset, since it
> increases conformance?

In C++ Builder you can use a #pragma to ensure enum size from within a
header file using enums no matter how the -b option is set by the user. This
ensures binary compatibility. I use this technique all the time with enums
in my own Borland header files. The Regex++ library uses it also as Dr.
Maddock can affirm.

#pragma option push -b- // or #pragma option push -b

// enum(s) here

#pragma option pop

>
> Gennaro Prota <gennaro_prota_at_[hidden]> writes:
>
> > On Sun, 26 Jan 2003 10:05:51 -0500, "Edward Diener"
> > <eddielee_at_[hidden]> wrote:
> >
> >>For Borland, the default is to make enum's int sized but this can be
changed
> >>with the -b- option in which enums are made as small as possible
depending
> >>on the range.
> >
> > Yes. The original problem, anyhow, was not about making them small but
> > making them large and giving them the right signedness, like in:
> >
> >    enum { e = 2147483648u };
> >
> > Actually the -b- option also has this effect (thus with that option e
> > < 0 would yield false, as required by C++) but the help file provided
> > with Borland command line tools has an error that can be misleading in
> > that regard. It says:
> >
> >
> >    When this option is off (-b-), the compiler allocates the
> >    smallest integer that can hold the enumeration values:
> >    the compiler allocates an unsigned or signed char if the values
> >    of the enumeration are within the range of 0 to 255 (minimum) or
> >    -128 to 127 (maximum), or an unsigned or signed short if the values
> >    of the enumeration are within the following ranges:
> >
> >      0 to 4,294,967,295 or -2,147,483,648 to 2,147,483,647
> >
> >
> > It seems to refer only to types not larger than int, leading to think
> > that -b- is just a space optimization. Instead it also concerns sign.
> >
> > Note the last sentence: the ranges are those of unsigned and signed
> > *int*, not short :-) Probably there's a whole part in the middle that
> > got lost for some reason, which should be:
> >
> >    ..unsigned or signed short if the values... are within
> >
> >      0 to 65535  or -32768 to 32767
> >
> >    or an unsigned or unsigned *int* if they are in
> >    the range
> >
> >
> >      0 to 4,294,967,295 or -2,147,483,648 to 2,147,483,647
> >
> >
> > Genny.
> >
> > _______________________________________________
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>
> --
>                        David Abrahams
>    dave_at_[hidden] * http://www.boost-consulting.com
> Boost support, enhancements, training, and commercial distribution
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