Re: [boost] numeric_cast

Subject: Re: [boost] numeric_cast
From: Paul A. Bristow (pbristow_at_[hidden])
Date: 2011-07-11 11:53:14

Sorry for last response  (I have just got back from holiday :-)

I suspect we are all agreed this is correct?

If so should it go into our  Boost style 'recommendations' docs somewhere?

Paul

---
Paul A. Bristow,
Prizet Farmhouse, Kendal LA8 8AB  UK
[phone]  07714330204
pbristow_at_[hidden]
> -----Original Message-----
> From: boost-bounces_at_[hidden] [mailto:boost-bounces_at_[hidden]] On Behalf Of Stephan T.
> Lavavej
> Sent: Thursday, June 23, 2011 10:43 PM
> To: boost_at_[hidden]
> Subject: Re: [boost] numeric_cast
> 
> [Fernando Cacciola]
> > It looks fine to me (except maybe for the #pragma once... is that
> > properly supported on all supported compilers?)
> 
> [Brandon Kohn]
> > Ah, right. We use that at my work (all MSVC). So I'm acclimated. I'll
> > remove those.
> 
> Actually, the best thing to do is this:
> 
> #ifndef MYPROJECT_MYDIRECTORY_FOOBAR_HPP #define MYPROJECT_MYDIRECTORY_FOOBAR_HPP
> 
> #ifdef _MSC_VER
>     #pragma once
> #endif // _MSC_VER
> 
> meow;
> 
> #endif // MYPROJECT_MYDIRECTORY_FOOBAR_HPP
> 
> This way, all compilers get the portable idempotency guard. Because it's on the outside, GCC (and
possibly
> other compilers) will magically recognize it and avoid opening the header file twice. And the
#pragma once
> for MSVC also instructs it to avoid opening the header file twice, which can improve build perf
and can't
> hurt.
> 
> Stephan T. Lavavej
> Visual C++ Libraries Developer
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