Commits on Apr 10, 2015

1. Make __dict__ accessible for Python builtin classes …

   Attribute set within instance of a SWIG Python wrapped class are
   stored in SwigPyObject->dict, which tp_dictoffset slot is pointing to.
   
   However, SWIG wrapped classes did not have a __dict__ attribute.
   Inheriting subclasses did not get the attribute either because the
   SWIG wrapped classes initialize the tp_dictoffset slot:
   
   From http://bugs.python.org/issue16272:
   
   "If a type defines a nonzero tp_dictoffset, that type is responsible for
   defining a `__dict__` slot as part of the tp_getset structures. Failure to
   do so will result in the dict being inaccessible from Python via
   `obj.__dict__` from instances of the type or subtypes."
   
   Provide a SwigPyObject_get___dict__() function to retrieve the dict
   attribute or create it when it does not exist yet (it is normally
   created when setting attribute set), and a PyGetSetDef entry pointing
   to this function.

   

   amaeldoe committed Apr 10, 2015
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2. Fix SwigPyObject->dict memory leak …

   The following patch attempt to fix a memory leak happening when a
   random class attribute is set. The internal instance dictionary is
   created but never freed.
   
   This fixes the problem for me, although I am not sure the patch
   is correct.
   
   <code>
    p = MySWIGClass()
    p.random_attribute = 0
   </code>
   
   Valgrind report:
   ==18267== 280 bytes in 1 blocks are definitely lost in loss record 1,372 of 1,780
   ==18267==    at 0x4A0645D: malloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
   ==18267==    by 0x3A90A885DC: PyObject_Malloc (in /usr/lib64/libpython2.7.so.1.0)
   ==18267==    by 0x3A90B101A8: _PyObject_GC_Malloc (in /usr/lib64/libpython2.7.so.1.0)
   ==18267==    by 0x3A90B102AC: _PyObject_GC_New (in /usr/lib64/libpython2.7.so.1.0)
   ==18267==    by 0x3A90A80943: PyDict_New (in /usr/lib64/libpython2.7.so.1.0)
   ==18267==    by 0x3A90A6E8FC: PyFrame_New (in /usr/lib64/libpython2.7.so.1.0)
   ==18267==    by 0x3A90AE1A65: PyEval_EvalCodeEx (in /usr/lib64/libpython2.7.so.1.0)
   ==18267==    by 0x3A90AE088E: PyEval_EvalFrameEx (in /usr/lib64/libpython2.7.so.1.0)
   ==18267==    by 0x3A90AE21DC: PyEval_EvalCodeEx (in /usr/lib64/libpython2.7.so.1.0)
   ==18267==    by 0x3A90AE22E1: PyEval_EvalCode (in /usr/lib64/libpython2.7.so.1.0)
   ==18267==    by 0x3A90AFB71E: ??? (in /usr/lib64/libpython2.7.so.1.0)
   ==18267==    by 0x3A90AFC8DD: PyRun_FileExFlags (in /usr/lib64/libpython2.7.so.1.0)
   ==18267==

   

   amaeldoe committed Apr 10, 2015
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3. Attribute of SWIG wrapped classes instances were overwritten on __ini… …

   …t__()
   
   When a SWIG classes instances is initialized, its internal dictionary was
   reset to NULL, which result in the loss of any attribute that might have
   been set for the instance.
   
   Only initialize the internal dictionary on actual PyObject creation.
   
   class Test(MySwigWrappedClass):
           def __init__(self):
                   self.val = "Random Value"
                   MySwigWrappedClass.__init__(self)
   
   p = Test()
   print hasattr(p, "val") # Should return True, but used to return False

   

   amaeldoe committed Apr 10, 2015
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