Troy Curtis Jr wrote on Sat, 23 Dec 2017 15:27 +0000: > On Fri, Dec 22, 2017 at 11:11 PM Daniel Shahaf <[email protected]> > wrote: > > > [email protected] wrote on Sat, 23 Dec 2017 04:43 +0000: > > > Author: troycurtisjr > > > Date: Sat Dec 23 04:43:26 2017 > > > New Revision: 1819110 > > > > > > URL: http://svn.apache.org/viewvc?rev=1819110&view=rev > > > Log: > > > On branch swig-py3: Replace hasattr check for a method with try-except. > > > > > > * subversion/bindings/swig/include/proxy.swg > > > (_assert_valid_deep): Replace hasattr check for the 'assert_valid' > > method > > > with a try-except block as some class instances can have the method > > but return > > > False to hasattr(). > > > > I'm not too familiar with this code; shouldn't we be fixing the original > > problem, of hasattr() wrongly returning False? I assume it predates the > > branch, though? > > > > > I won't lie, I didn't like this change much, since I didn't feel that I > understood exactly *why* it didn't work. I only found info stating that > hasattr effectively did a getattr, but translated the AttributeError into a > boolean. However, obviously *something* else is different. The attribute > is obviously able to be found in some scenarios, but returns false for > hasattr. So far my attempts to reproduce in a small test class haven't > been successful. Perhaps, I should continue to dig into this one to get to > the bottom of what the difference actually is.
I assume it could affect users' code as well, so yes, it'll be nice to get to the bottom of it (and to confirm that it's not a regression). What classes can you reproduce the mismatch with? I don't see any difference between the CPython implementations of getattr and hasattr, but perhaps I'm overlooking something (or looking at the source of a different CPython version to yours). > > > While reviewing this I also noticed that svn_swig_py_convert_ptr() also > > does this hasattr() check — not sure whether it needs to change too? — > > and also has an "x | 0" construct, which seems suspicious (isn't it a > > no-op?). > > > > > I looked back through the logs in an attempt figure out the rationale for > the "x | 0" construct, but it just shows up that way when it was first > added [0]. I agree, it should just be changed to the define. I can't come > up with a reason to 'or' with 0. SWIG_POINTER_EXCEPTION is defined as «0» in swig3 so the construct does appear to be a no-op there. I don't have older swigs to test with. (@brane: Good catch.) > 0: svn diff -r855533:855534 > ^/subversion/branches/python-bindings-improvements/subversion/bindings/ > swig/python/libsvn_swig_py/swigutil_py.c@855534 Also known as https://svn.apache.org/viewvc/subversion/branches/python-bindings-improvements/subversion/bindings/swig/python/libsvn_swig_py/swigutil_py.c?r1=855534&r2=855533&pathrev=855534 Cheers, Daniel
