[Python-Dev] Avoid formatting an error message on attribute error (original) (raw)

Serhiy Storchaka storchaka at gmail.com
Thu Nov 7 13:19:18 CET 2013

07.11.13 00:32, Victor Stinner написав(ла):

I'm trying to avoid unnecessary temporary Unicode strings when possible (see issue #19512). While working on this, I saw that Python likes preparing an user friendly message to explain why getting an attribute failed. The problem is that in most cases, the caller doesn't care of the message: the exception is simply deleted. For example, hasattr() deletes immediatly the AttributeError.

It would be nice to only format the message on demand. The AttributeError would keep a reference to the type. Keeping a strong reference to the type might change the behaviour of some applications in some corner cases. (Holding a reference to the object would be worse, and the type looks to be preferred over the type to format the error message.)

See also:

http://bugs.python.org/issue18156 : Add an 'attr' attribute to AttributeError http://bugs.python.org/issue18162 : Add index attribute to IndexError http://bugs.python.org/issue18163 : Add a 'key' attribute to KeyError

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