[Python-3000] Could isinstance/issubclass overriding be dangerous? (original) (raw)
Guido van Rossum guido at python.org
Mon Apr 30 06:05:23 CEST 2007
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On 4/29/07, Greg Ewing <greg.ewing at canterbury.ac.nz> wrote:
Currently, isinstance(x, C) implies that the C struct layout of x is compatible with that defined by C. I'm worried that changing this could cause difficulties for extension modules that use PyObjectIsInstance do decide what to do with things, e.g. in a binary operator method.
Unless they were looking at classic classes, why wouldn't they be using the specific Py_Check() macros? If you want this argument to be taken serious, use Google code search (code.google.com) or a similar source code search engine to find examples that would break.
Again, the only envisioned overloading is where the 2nd argument is an ABC.
Also, note that PyObject_IsInstance already returns abstract results when the first argument is a proxy instance.
-- --Guido van Rossum (home page: http://www.python.org/~guido/)
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