[forwarding to cython-devel] Wouter Bolsterlee, 02.02.2014 16:40: > Cython 0.20 introduced __Pyx_PyObject_LookupSpecial as a shortcut to > lookup special methods. The commit that introduced this change is > 8f6412275c4c2d1dcf43ad40306f858b114104ed and can be seen here: > > https://github.com/cython/cython/commit/8f6412275c4c2d1dcf43ad40306f858b114104ed > > It seems this change does not work with Python 2.6. The newly introduced > function calls _PyType_Lookup(), which fails to lookup (at least) > __exit__ (on a threading.Lock) instance when run under Python 2.6. The > exact call is here: > > https://github.com/cython/cython/commit/8f6412275c4c2d1dcf43ad40306f858b114104ed#diff-83083bdce5dcca284394ead83b8d3f99R1053 > > For my Plyvel project (https://plyvel.readthedocs.org/ and > https://github.com/wbolster/plyvel) this issue manifests as follows: > > $ cython --version > Cython version 0.20 > > $ python > Python 2.6.8 (unknown, Jan 26 2013, 14:35:25) > [GCC 4.7.2] on linux2 > Type "help", "copyright", "credits" or "license" for more > information. > >>> import plyvel > >>> db = plyvel.DB('/tmp/testdb', create_if_missing=True) > >>> db.close() > Traceback (most recent call last): > File "<stdin>", line 1, in <module> > File "_plyvel.pyx", line 246, in plyvel._plyvel.DB.close > (plyvel/_plyvel.cpp:3563) > File "_plyvel.pyx", line 252, in plyvel._plyvel.DB.close > (plyvel/_plyvel.cpp:3221) > AttributeError: __exit__ > >>> > Exception AttributeError: '__exit__' in > 'plyvel._plyvel.DB.__dealloc__' ignored > > The same Cython source code works fine against Python 2.7, 3.2, and 3.3. > Reverting to Cython 0.19 makes the code run correctly on Python 2.6, > 2.7, 3.2, and 3.3 again. This means only the combination of Python 2.6 > and Cython 0.20 fails. > > To check for yourself, you can run "make test" on a Git clone of Plyvel > with either Cython 0.19 or Cython 0.20 installed, and spot the > differences. Or run "tox" to automatically test against multiple Python > versions.
Ok, I don't know what the exact difference is, but I do believe you that Py2.6 doesn't play as nicely here as Py3. In any case, the CPython code that I adapted it from didn't actually exist in Py2.6/3.1, so the guarantees don't need to be there either. Given that this is essentially an optimisation (and otherwise meant to *improve* the compatibility with CPython's own behaviour), I'll disable this in Py2.6 and Py3.1 for the next bug fix release. https://github.com/cython/cython/commit/b8e37bc15373f303691de2d256ad99045221c9e0 It would be good if you could come up with a failing regression test case for this, so that we can make sure it actually keeps working in the future. > Please CC me when responding, because I'm not subscribed to > cython-devel. cython-devel is actually fairly low traffic, so temporarily subscribing to it won't hurt much. Stefan _______________________________________________ cython-devel mailing list cython-devel@python.org https://mail.python.org/mailman/listinfo/cython-devel
