Re: [boost] [config] Macro for null pointer

Subject: Re: [boost] [config] Macro for null pointer
From: Vicente Botet (vicente.botet_at_[hidden])
Date: 2012-11-16 08:04:11

Jeffrey Lee Hellrung, Jr.-2 wrote
> On Thu, Nov 15, 2012 at 7:04 PM, Edward Diener <

> eldiener@

> >wrote:
> 
>> I have found something like this to be helpful, when working with
>> multiple
>> compilers:
>>
>> #include <boost/config.hpp>
>> #if defined(BOOST_NO_NULLPTR)
>> #define BOOST_XXX_NULLPTR 0
>> #else
>> #define BOOST_XXX_NULLPTR nullptr
>> #endif
>>
>> where XXX is some local name for my own use. And then use
>> BOOST_XXX_NULLPTR in places where a null pointer is needed.
>>
>> Would this be a candidate for a BOOST_NULLPTR macro in the config library
>> instead ?

+1.

> Might it be better to just offer a (albeit imperfect) nullptr emulation if
> not supplied by the compiler? For example, [1].
> 
> [1] http://en.wikibooks.org/wiki/More_C%2B%2B_Idioms/nullptr

There are two levels that can be addressed by different approaches:

* write portable code that uses C++11 nullptr when available and 0
otherwise.
* write portable code that uses C++11 nullptr when available and something
safer than 0 or NULL is used to represent a null pointer otherwise.

The PO proposal corresponds to the first level, whilc IMO is already
interesting.
The more elaborated proposal corresponds to the second need.

I will be for a direct inclusion of the BOOST_NULLPTR macro as part of the
Boost.Config helpers, and why not accept a specific nullptr implementation
if someone is ready to maintain it.

Best,
Vicente

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