Re: [boost] numeric_cast

Subject: Re: [boost] numeric_cast
From: Mateusz Loskot (mateusz_at_[hidden])
Date: 2011-06-27 12:29:05

On 24/06/11 11:46, Antony Polukhin wrote:
> 2011/6/24 Tom Tan<ttan_at_[hidden]>:
>> It seems to me the outer #ifdef works for MSVC as well. What's the extra
>> benefit of embedding an inner #pragma once in this case?
>
> In case there is no pragma in header, compiler will open header file
> again when it is included and will parse it till include guards.
> If there is a pragma, compiler will not open and parse the file again.
> So pragma can reduce compilation time.

Do you mean Visual C++ specific behaviour?
Is location of #pragma relevant? Meaning, having #pragma nested in 
#ifndef include guard vs. placing it in outer scope, makes difference or 
not?

Best regards,
-- 
Mateusz Loskot, http://mateusz.loskot.net
Charter Member of OSGeo, http://osgeo.org
Member of ACCU, http://accu.org