[Python-Dev] Small misleadingness in docs (original) (raw)

Raymond Hettinger python at rcn.com
Sat Feb 14 02:40:19 CET 2009

[Greg Ewing]

I've discovered something slightly misleading in the docs for PyObjectIsInstance:

When testing if B is a subclass of A, if A is B, PyObjectIsSubclass returns true. If A and B are different objects, B‘s bases attribute is searched... This suggests that issubclass(A, A) will always be true, regardless of what attributes A has. However, this turns out not to be so -- A must also have a bases attribute, otherwise it's rejected as not being sufficiently class-like.

This smells like a bug that brings issubclass() out of sync with isinstance(). Perhaps issubclass() should do what the docs say and start by testing whether A and B are the same object.

Raymond

More information about the Python-Dev mailing list