On 08.11.2012 13:47, Stefan Behnel wrote: > Hi, > > I suspect that this will be put into a proper PEP at some point, but I'd > like to bring this up for discussion first. This came out of issues 13429 > and 16392. > > http://bugs.python.org/issue13429 > > http://bugs.python.org/issue16392 > > Stefan > > > The problem > =========== > > Python modules and extension modules are not being set up in the same way. > For Python modules, the module is created and set up first, then the module > code is being executed. For extensions, i.e. shared libraries, the module > init function is executed straight away and does both the creation and > initialisation. This means that it knows neither the __file__ it is being > loaded from nor its package (i.e. its FQMN). This hinders relative imports > and resource loading. In Py3, it's also not being added to sys.modules, > which means that a (potentially transitive) re-import of the module will > really try to reimport it and thus run into an infinite loop when it > executes the module init function again. And without the FQMN, it's not > trivial to correctly add the module to sys.modules either. > > We specifically run into this for Cython generated modules, for which it's > not uncommon that the module init code has the same level of complexity as > that of any 'regular' Python module. Also, the lack of a FQMN and correct > file path hinders the compilation of __init__.py modules, i.e. packages, > especially when relative imports are being used at module init time. > > The proposal > ============ > > ... [callbacks] ... > > Alternatives > ============ > ... > 3) The callback could be registered statically in the PyModuleDef struct by > adding a new field. This is not trivial to do in a backwards compatible way > because the struct would grow longer without explicit initialisation by > existing user code. Extending PyModuleDef_HEAD_INIT might be possible but > would still break at least binary compatibility.
I think the above is the cleaner approach than the callback mechanism. There's no problem in adding new slots to the end of the PyModuleDef struct - we've been doing that for years in many other structs :-) All you have to do is bump the Python API version number. (Martin's PEP http://www.python.org/dev/peps/pep-3121/ has the details) -- Marc-Andre Lemburg eGenix.com Professional Python Services directly from the Source (#1, Nov 08 2012) >>> Python Projects, Consulting and Support ... http://www.egenix.com/ >>> mxODBC.Zope/Plone.Database.Adapter ... http://zope.egenix.com/ >>> mxODBC, mxDateTime, mxTextTools ... http://python.egenix.com/ ________________________________________________________________________ ::: Try our new mxODBC.Connect Python Database Interface for free ! :::: eGenix.com Software, Skills and Services GmbH Pastor-Loeh-Str.48 D-40764 Langenfeld, Germany. CEO Dipl.-Math. Marc-Andre Lemburg Registered at Amtsgericht Duesseldorf: HRB 46611 http://www.egenix.com/company/contact/ _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
