Py_TPFLAGS_HAVE_CLASS in ExtensionClass.h about extensionclass HOT 3 CLOSED

I don't know the answers, but anecdotally, I was just able to get AccessControl to build by changing its copy of ExtensionClass.h to use HAS_TP_DESCR_GET here, even without including _compat.h anywhere new.

from extensionclass.

From my point of view this whole macro is very dangerous and the best would be to get rid of it.
PyMem_DEL is meant to delete an arbitrary chunk of data. See here https://docs.python.org/3.5/c-api/memory.html?highlight=pymem_del#c.PyMem_Del

With this redefinition we change the meaning to: "Free an object". So if people use PyMem_Del as documented in the python docu they are risking segfaults.

Mapping PyObject_DEL to PyMem_DEL is also dangerous, because different allocators are used behind the scenes.
According to this https://docs.python.org/2/whatsnew/2.5.html PyObject_XX and PyMEM_XX cannot be mixed anymore.
With 2.5’s changes to obmalloc, these families now do different things and mismatches will probably result in a segfault. You should carefully test your C extension modules with Python 2.5

I searched where PyMem_Del is used inside zopefoundation code.
https://github.com/search?q=org%3Azopefoundation+PyMem_DEL&type=Code
The only occurrence is in ExtensionClass.h copied to the various repos using ExtensionClass.
The same is true for PyObject_FREE.

I guess back at the days, when new style classes were introduced, there was a use for this macro.
Hence the comment, but nowadays they have no use.

So if nobody objects I'll prepare a pull request to get rid of this macros.

from extensionclass.

+1 for removing the macro

from extensionclass.