Re: [boost] __COUNTER__ vs __LINE__

Subject: Re: [boost] __COUNTER__ vs __LINE__
From: Christopher Jefferson (chris_at_[hidden])
Date: 2012-01-11 13:44:18

On 11 Jan 2012, at 18:28, lcaminiti wrote:

> Hello all,
> 
> Many of Boost macro APIs PP_CAT symbols with either __LINE__ or __COUNTER__
> to make them unique (MPL_STATIC_ASSERT, SCOPE_EXIT, etc). AFAIK, __LINE__ is
> C++03 standard while __COUNTER__ is only a MSVC extension. I think using
> __COUNTER__ instead of __LINE__ might allow to expand a macro multiple times
> on the same line... but a  part from that:
> 
> What's the reason for using __COUNTER__ on MSVC instead of just using
> __LINE__ for all compilers?

__LINE__ is restarted for each header file separately, so you can get problems with using a macro on the same line number of different files. I've been bitten by this before. __COUNTER__ is superior.

Chris