[C++-sig] Multiple calls to bp::detail::init_module() causing conflicts?

[Ralf W. Grosse-Kunstleve]

Hi Austin,
Just a remark: the python3 support isn't routinely exercised.
Overlooked incompatibilities are possible.
I only have time to maintain the python2 support. We need a
volunteer to port the unit tests to python3.
Ralf



----- Original Message ----
> From: Austin Bingham <austin.bingham at gmail.com>
> To: Development of Python/C++ integration <cplusplus-sig at python.org>
> Sent: Mon, December 20, 2010 7:04:06 AM
> Subject: [C++-sig] Multiple calls to bp::detail::init_module() causing 
>conflicts?
> 
> I'm in the process of upgrading my project to boost-1.45.0 and
> python3, and I  started seeing strange problems with some of my
> boost.python-based extension  modules. Essentially, some of my modules
> are reporting the wrong module name,  i.e. if I
> "print(module_object.__name__)", I get the wrong value. I threw  this
> into gdb, and it looks like the problem might have to do with  the
> implementation of bp::detail::init_module().
> 
> I ran python under  gdb, but a breakpoint on init_module(), and
> imported the modules with which  I'm seeing problems. The first call to
> init_module() initializes the static  PyModuleDef struct "moduledef"
> properly. However, the second call shows that  the "m_name" field it
> left as-is from the first call (since the object is  static); I would
> have expected that it needs to be updated with the new  module name.
> This stale (I think) module def is then used for the rest of  the
> initialization, and I'm guessing that this is the cause of  the
> problems I'm seeing. Certainly, it seems that the name of the  first
> module imported seems to be getting used as the name of the  second
> module.
> 
> I only noticed this problem when I tried to pickle some  of the types
> exposed by my module. The pickle module in python3 complained  that it
> didn't know anything about the broken modules I was  getting.
> 
> Is this a bug in boost.python? I plan to write a small patch  tomorrow
> to set the m_name field in init_module(), so maybe this will fix  the
> problem.
> 
> If this isn't a boost.python bug, does anyone have any  idea what might
> be going wrong? And how is it correct that the static  moduledef is
> reused without updating its  name?
> 
> Thanks,
> Austin
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