Re: [boost] Proposal for #pragma once support

Subject: Re: [boost] Proposal for #pragma once support
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2009-06-09 15:00:00

Zachary Turner wrote:
On Tuesday, June 09, 2009 2:55 PM
> On Tue, Jun 9, 2009 at 1:41 PM, Stewart, Robert
> <Robert.Stewart_at_[hidden]>wrote:
> > Zachary Turner wrote
> > On Tuesday, June 09, 2009 2:30 PM
> > >
> > > And perhaps the best approach is what I mentioned in a previous
> > > post, to force the programmer to explicitly define
> > > BOOST_USE_PRAGMA_ONCE before including a boost header file.
> > > This would solve the problem of having to modify every header
> > > when new compilers were released.
> >
> > I agree that a single manifest constant to control using
> > #pragma once is the right thing to do.  However, the scheme
> > you describe here puts too much onus on the Boost user.  Why
> > not define that manifest constant on the compiler command
> > line using Boost.Build?  You can define that for each
> > compiler, unless I'm much mistaken.
>
> Having almost no familiarity whatsoever with Boost.Build, can
> you elaborate a little bit more?  Are you referring to building
> the boost libraries themselves, or building a project that uses
> boost with a custom makefile, project, etc?

It was a faulty idea since it would only affect the libraries with linked binaries.  Given that most of Boost is header based, the idea is that the Boost user must change their own build system's command line to define that manifest constant.  For those using Boost.Build to build their own code, the change I mentioned would apply automatically to building Boost libraries and the developer's own code.

_____
Rob Stewart                           robert.stewart_at_[hidden]
Software Engineer, Core Software      using std::disclaimer;
Susquehanna International Group, LLP  http://www.sig.com

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