Re: [boost] numeric_cast

Subject: Re: [boost] numeric_cast
From: Edward Diener (eldiener_at_[hidden])
Date: 2011-06-27 19:27:43

On 6/27/2011 6:01 PM, Kim Barrett wrote:
> On Jun 27, 2011, at 5:03 PM, Lars Viklund wrote:
>> On Mon, Jun 27, 2011 at 04:42:43PM -0400, Edward Diener wrote:
>>> I doubt if any compiler cares where the #ifndef ( or #if !defined ) is.
>>
>> I would reckon that compilers and preprocessor implementations may have
>> fast-paths that they go into if they detect something that looks like an
>> include guard very early in the file, where they can cheaply reject it
>> if already included with a minimum of work, if they guarantee
>> correctness.
>>
>> After, all, it's a very common operation, it's most probably very
>> beneficial for cutting preprocessing costs.
>
>
> http://gcc.gnu.org/onlinedocs/cppinternals/Guard-Macros.html

I stand corrected.