Re: [boost] Proposal for #pragma once support

Subject: Re: [boost] Proposal for #pragma once support
From: Scott McMurray (me22.ca+boost_at_[hidden])
Date: 2009-06-09 23:33:46

2009/6/9 Emil Dotchevski <emildotchevski_at_[hidden]>:
>
> You're making the same point I was thinking about earlier, which is
> that in theory #pragma once shouldn't be faster than include guards.
> So how about this:
>
> #include <boost/detail/workaround.hpp>
> #if defined(BOOST_MSVC) && BOOST_WORKAROUND(BOOST_MSVC, < 1500)
> #pragma once
> #endif
>

Other than the fact that this should just be solved for once and for
all in MSVC, rather than forcing us to pollute our code, I don't see a
problem with just using this:

#ifdef BOOST_ENABLE_PRAGMA_ONCE
#pragma once
#endif

That way anyone who wants it can have it, and it's obvious by looking
at the headers how to get it, but we're not encouraging its use.