Re: [boost] [threads] namespace & externs

Subject: Re: [boost] [threads] namespace & externs
From: Scot Shinderman (scot_at_[hidden])
Date: 2011-01-26 20:33:36

Anthony Williams <anthony.ajw <at> gmail.com> writes:

> 
> scot shinderman <scot <at> imageworks.com> writes:
> 
> >     In boost/thread/src/pthread/thread.cpp we see extern "C" {}
> > around code such as tls_destructor.  Is this needed so it
> > interfaces w/ native pthread local storage?
> 
> Yes.
> 
> >      When a vendor program is built against a specific version
> > of boost it usually becomes necessary to isolate other users
> > via a namespace.  However, anything with extern "C"
> > style defeats this.  Aside from explicit linking to native c
> > api's are there reasons for this; also what's considered the best
> > style to isolate different versions -- currently we modify every header
> > with a version-ed namespace wrapper.
> 
> extern "C" is only used where it is necessary (at least, that is the
> intent). If you need the extern "C" stuff to be versioned then you'll
> have to rename it. Renaming the namespace seems a sensible option for
> the rest of the code.

A little confused by this last part -- if the routine tls_destructor can be
renamed something i.e. tls_destructor_v2 then why does it need to be extern "C"
at all (why wouldn't the name-mangled version work as well)?   If the pthread
library cannot find something called tls_destructor what will occur?     So far
in small tests we haven't seen problems;  with our vendor's version of boost
however thrown into the mix something stills seems awry especially during thread
tear down...

thanks!

> 
> Anthony