[boost] Re: Fwd: Stdint header?

From: Thomas Plum (tplum_at_[hidden])
Date: 1999-08-05 11:03:33

I want to provide some arguments for making use of, and encouraging
the use of, the <stdint.h> as defined in C9X (or indirectly thru a
boost-specific <stdint.hpp> or whatever).

First is a process issue.  As liaison from WG21, I communicated to
WG14 that C++ was very unhappy with the original structure of
<stdint.h> in which typedefs and macros were all swizzled together.
The liaison from C++ was to subdivide the header, so that C++ can
use the typedefs without the macros.  It took some convincing, but
this particular liaison request did pass.  I think it's bad manners
to then decide to dump the result without a very strong functional
reason.

However, that argument might persuade no one but me, so I have 
others.  There is a maintenance cost, and a political cost, to each
feature of a standard or of an API.  The <stdint.h> header was one
of the few features of C9X that was already in widespread use at
many sites, and it was also being widely used in the C++ implementations
at those sites.  If boost, or C++ at large, defines some alternative
to <stdint.h>, then those two alternatives compete for maintenance
and political support.  

If we were talking about important functional differences, then I
would think differently about that competition.  But we are talking
about the same functionality ... defining exact/least/fast/etc types
for a specific set of integer bit widths.  Whether the name of the
type is spelled  int_exact<32>::type  or  int32_t  or whatever, there
must be a one-line typedef somewhere in some header that defines that
type.  Well, actually if everyone uses <stdint.h> (or indirectly via
<cstdint> ), there exists only one such typedef per type to be maintained,
but if C and C++ have different headers then there exist two such
typedefs for each type.

Just a plea to focus the creative effort upon the other problems, where
there is clearly no opportunity for common C/C++ solutions ...

>Reply-To: boost_at_[hidden]
>Delivered-To: listsaver-egroups-boost_at_[hidden]
>X-Lotus-FromDomain: QATRAIN
>From: "Kevlin Henney" <Kevlin.Henney_at_[hidden]>
>To: boost_at_[hidden]
>Date: Wed, 4 Aug 1999 07:21:19 +0100
>Subject: [boost] Re: Stdint header?
>
>Beman Dawes wrote:
>>Kevlin, what did your template approach look like?
>>
>>     int_exact<32>::type
>>     int_least<32>::type
>
>That strikes me as better than having a single type with
>exact/least/fast/etc types embedded.  Not sure exactly why, but my
>gut feeling is it would extend better.
>
>   Yes, gut feelings count for a lot on this one. These are effectively
>   inverse traits, in the sense that a trait is being used to look up a
>   type (rather than the other way around, as for traits) and so naming the
>   inverse trait directly as the template name separately seemed a more
>   reasonable approach.
>
>   I also felt this was more extensible and more fine grained than offering
>   the user a basket of types, especially as the mechanisms employed for
>   each looked up type are quite different: simple specialisation vs a
>   'looping' search.
>
>   Kevlin
>
>
>
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