Bugs item #942706, was opened at 2004-04-27 01:39
Message generated for change (Comment added) made by birkenfeld
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Category: Python Interpreter Core
Group: Python 2.3
Status: Open
Resolution: None
Priority: 5
Submitted By: has (hhas)
Assigned to: Nobody/Anonymous (nobody)
Summary: Python crash on __init__/__getattr__/__setattr__ interaction
Initial Comment:
The following code causes [Mac]Python 2.3 process to crash
(Bad!) rather than raise an error (good) when creating a new
instance of Foo:
class Foo:
def __init__(self):
self.x = 1
def __getattr__(self, name):
if self.x:
pass # etc...
def __setattr__(self, name, val):
if self.x:
pass # etc...
(See <http://freespace.virgin.net/hamish.sanderson/
HTMLTemplate-0.4.0.tar.gz> for a working example plus general
solution to the referencing-instance-var-before-it's-created
paradox that threw up this bug in the first place.)
----------------------------------------------------------------------
>Comment By: Georg Brandl (birkenfeld)
Date: 2006-01-10 22:56
Message:
Logged In: YES
user_id=1188172
To the OP: Is there still a crash with newest Python 2.4?
----------------------------------------------------------------------
Comment By: Walter Dörwald (doerwalter)
Date: 2004-06-02 21:17
Message:
Logged In: YES
user_id=89016
Assigning to self.x in __init__() calls __setattr__(), which
checks self.x, which calls __getattr__() which checks self.x,
which leads to endless recursion. This usually leads to
a "RuntimeError: maximum recursion depth exceeded". In what
way does Python 2.3 crash?
To avoid the recursion access the instance dictionary directly:
class Foo:
def __init__(self):
self.x = 1
def __getattr__(self, name):
if "x" in self.__dict__ and self.__dict__["x"]:
pass # etc...
def __setattr__(self, name, val):
if self.x:
pass # etc...
----------------------------------------------------------------------
You can respond by visiting:
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=942706&group_id=5470
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