Subject: Re: [boost] [system] Header-only Boost.System by default ?
From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2017-10-10 19:30:49
On 10/10/17 22:27, Mike Gresens via Boost wrote:
> Am 10.10.2017 um 10:21 schrieb Groke, Paul via Boost:
>>> -----Original Message-----
>>> From: Boost [mailto:boost-bounces_at_[hidden]] On Behalf Of Andrey
>>> Semashev via Boost
>>> Sent: Dienstag, 10. Oktober 2017 09:32
>>> Subject: Re: [boost] [system] Header-only Boost.System by default ?
>>> It will have the same address as long as get_basic_error_category()
>>> is called
>>> within the same module (dll, so, exe, etc.) If this function is
>>> compiled in
>>> different modules then there will be multiple instances of the
>>> category with
>>> different addresses.
>>> On Linux and probably other Unix-like systems this can be solved by
>>> exporting the category instance, which is the default. I don't think
>>> this can be
>>> done on Windows - you'd have to export get_basic_error_category for that
>>> instead and it will make this code less friendly to header-only
>> And even if the "same address" thing was solvable (which I think it
>> is, although not pretty and it would require interface changes), there
>> is the problem with unloading DLLs/SOs. You'd have to pin every module
>> that contains error categories. Which IMO is a side effect that you
>> really don't expect and want, especially from a header-only library.
> How does libstdc++ (>= C++11) solve these problems?
libstdc++ is not header-only, you link with libstdc++.so.
Boost list run by bdawes at acm.org, gregod at cs.rpi.edu, cpdaniel at pacbell.net, john at johnmaddock.co.uk