[Python-Dev] Exceptions and slicing (original) (raw)

"Martin v. Löwis" martin at v.loewis.de
Wed Sep 20 21:58:36 CEST 2006

Thomas Heller schrieb:

1. The str of a WindowsError instance hides the 'real' windows error number. So, in 2.4 "print errorinstance" would print for example:

[Errno 1002] Das Fenster kann die gesendete Nachricht nicht verarbeiten. while in 2.5: [Error 22] Das Fenster kann die gesendete Nachricht nicht verarbeiten.

That's a bug. I changed the string deliberately from Errno to error to indicate that it is not an errno, but a GetLastError. Can you come up with a patch?

2. How would one write portable exception handling for Python 2.4 and 2.5?

I have code like this: try: do something except WindowsError, details: if not details.errno in (TYPEEREGISTRYACCESS, TYPEECANTLOADLIBRARY): raise Doesn't work in 2.5 any longer, because I would have to use details.winerror instead of e.errno.

Portable code should do

def winerror(exc): try: return exc.winerror except AttributeError: #2.4 and earlier return exc.errno

and then

try: do something except WindowsError, details: if not winerror(details) in (TYPE_E_REGISTRYACCESS, YPE_E_CANTLOADLIBRARY): raise

Regards, Martin

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