[issue12085] subprocess.Popen.__del__ raises AttributeError if __init__ was called with an invalid argument list

[Guido van Rossum]

Guido van Rossum added the comment:

FWIW, using class attributes to ensure __del__ does not hit AttributeError when __init__ failed is more idiomatic than using three-argument getattr().

The reason: in general it is possible that __del__ calls almost any other method on a class (e.g. for a buffered I.O stream open for writing, __del__ might call close() which might attempt to flush the buffer).  It is not reasonable (and ugly :-) to use three-argument in all code that might be called by __del__.  But it is reasonable to use class attributes to pre-initialize instance variables set by __init__ to "safe" defaults like None.

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nosy: +gvanrossum

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<http://bugs.python.org/issue12085>
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