Re: [boost] Reforming Boost.System and <system_error> round 2

Subject: Re: [boost] Reforming Boost.System and <system_error> round 2
From: Peter Dimov (lists_at_[hidden])
Date: 2018-01-16 18:16:07

James E. King, III wrote:

> If you decide to change system_error / error_code please make it 
> header-only.

We went over this last time, and touched the question again this time; the 
specification of system_category() requires that a reference to the same 
object is returned, and in the presence of DLLs, the only way to guarantee 
this is to make Boost.System itself a DLL.

If we adopt a more relaxed attitude and change operator== for error_category 
to match (by using a similar technique there to what MS does in their 
<system_error>), we might be able to get header-only working in practice in 
this scenario (if one doesn't pay attention to the actual address of the 
category.)

But even if we do fix the header-only case, switching to header-only by 
default would still be a major change.