[Python-Dev] Problems with Python's default dlopen flags

Mark Hammond mhammond@skippinet.com.au
Sun, 5 May 2002 19:05:24 +1000

> I have a number of problems following your description, so let me try
> to guess. In no released version of Python, libpython is build as a
> shared library. However, I'll assume that you have build
> libpythonxy.so as a shared library, and that this library provides the
> symbols that normally the Python executable provides.

Thanks for the note!  I now realize I left critical information deep in the
body - I was using ActivePython as it is the only released version of Python
that comes with a version built as a shared library (along with a
traditional static one)

> In that case, using RTLD_GLOBAL is one option. It is quite safe to use
> here, since it clutters the global namespace primarily with symbols
> that all start with Py; those are unlikely to clash with other
> symbols. Using RTLD_GLOBAL is needed since extension modules search
> the Py symbols in the global namespace; they normally come from the
> executable.

OK - cool.  So you are saying that what I have done is reasonable (whereas I
assumed it was a nasty hack :)

> The other option is to explicitly link all extension modules against
> your libpythonxy.so. If that is done, you can drop the RTLD_GLOBAL.
> Of course, the standard build process won't link extension modules
> with libpythonxy.so, since that library does not even exist in the
> standard build process.

Right.  Notwithstanding that the distribution I used *does* have a
libpython, I see that the same extension modules are used by the static and
dynamic versions of the core, so therefore can't have that reference.

Thanks for the info - strangely enough, it appears it is not a "problem" at
all ;)