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

Subject: Re: [boost] [config] Macro for null pointer
From: Edward Diener (eldiener_at_[hidden])
Date: 2012-12-04 15:05:43

On 12/4/2012 1:10 PM, Eric Niebler wrote:
> On 12/4/2012 10:06 AM, Jeffrey Lee Hellrung, Jr. wrote:
>> Well I guess unless anyone speaks up opposed to globally injecting nullptr
>> into the global namespace, that's what I'll do (as I'm outvoted :)
>> Conditional on non-definition of a macro, of course.
>
> Please, no. The bind placeholders are bad enough.

The use of 'nullptr' is "global" in C++. Why should not the inclusion of 
a particular Boost header file, possibly emulating 'nullptr' for 
compilers that do not support it, also create a "global" 'nullptr'.

I totally agree that normally injecting anything into the global 
namespace is a very poor thing to do. But in this case we would be 
emulating something that is already "global" by the C++ standard.

The idea I believe is this: the end-user includes the Boost header file. 
If there is already an implementation of 'nullptr' for the particular 
C++ compiler beng used, absolutely nothing in the header file does 
anything. If there is not an implementation of 'nullptr' for the 
particular C++ compiler beng used, the end-user's use of 'nullptr' in 
his code is using the Boost implementation.

Expecting an end-user to both include the Boost header file and then 
somehow know or care whether or not his compiler supports 'nullptr' and 
do something more when it does not before he can use 'nullptr' in his 
code, seems to me to defeat the purpose of providing a nullptr emulation.