Author mattip
Recipients Alexander.Belopolsky, Arfrever, Robin.Schreiber, amaury.forgeotdarc, belopolsky, jcea, jhaberman, lekma, loewis, mattip, petr.viktorin, pitrou
Date 2021-09-11.16:55:03
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Message-id <1631379303.59.0.239783914379.issue15870@roundup.psfhosted.org>
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>> I wouldn't recommend [setting ob_type] after PyType_Ready is called.

> Why not?  What bad things will happen?  It seems to be working so far.

It breaks the unwritten contract that "once PyType_Ready is called, the C struct will not be modified". This is implemented in PyPy, since calling PyType_Ready creates the PyPy object in the interpreter based on the C structure. Any further changes will not be reflected in the PyPy interpreter object, so now the python-level and c-level objects do not agree what type(obj) is.

We have discussed this in the PyPy team, and would like to propose relaxing the contract to state that "if the c-level contents of an object are modified, PyType_Modified must be called to re-synce the python level and c-level objects"
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Date User Action Args
2021-09-11 16:55:03mattipsetrecipients: + mattip, loewis, jcea, amaury.forgeotdarc, belopolsky, pitrou, Arfrever, petr.viktorin, lekma, Alexander.Belopolsky, Robin.Schreiber, jhaberman
2021-09-11 16:55:03mattipsetmessageid: <1631379303.59.0.239783914379.issue15870@roundup.psfhosted.org>
2021-09-11 16:55:03mattiplinkissue15870 messages
2021-09-11 16:55:03mattipcreate