Re: Logging in __del__()
On Wed, 16 Jul 2008 12:38:50 +0100, Robert Rawlins wrote: So, am I right to assume that python will still handle its garbage disposal if I implement __del__(), it just handles circular references in a slightly different way, but to the same effect. Right? No. Circular references in objects with a `__del__()` implementation are not collected! Why are you using `__del__()` anyway? Are you aware of the promises that are *not* made! It's not guaranteed when the method is called nor if it is called at all! Ciao, Marc 'BlackJack' Rintsch -- http://mail.python.org/mailman/listinfo/python-list
Logging in __del__()
Guys, I'm trying to help trace when instances of particular classes are being destroyed by the garbage collector and thought the cleanest way would be to implement a logging call in __del__() on the class. However, I'm having an issue. I inject a logger instance into my class upon construction and set it to self.logger, I then use this within the class to log actions going on within, works fine. Now, when I make the call in the __del__() method like so: def __del__(self): # Log the classes destruction. self.logger.debug(Class Instance Destroyed) I then get the following exception thrown when running my code: Traceback (most recent call last): File /usr/lib/python2.5/logging/handlers.py, line 73, in emit if self.shouldRollover(record): File /usr/lib/python2.5/logging/handlers.py, line 147, in shouldRollover self.stream.seek(0, 2) #due to non-posix-compliant Windows feature ValueError: I/O operation on closed file Does anyone have any ideas as to what I'm doing wrong here? Is this a known issue which has a neat little work around? Cheers, Robert -- http://mail.python.org/mailman/listinfo/python-list
Re: Logging in __del__()
Robert Rawlins wrote: I then get the following exception thrown when running my code: When the application is running, or when it is shutting down? Traceback (most recent call last): File /usr/lib/python2.5/logging/handlers.py, line 73, in emit if self.shouldRollover(record): File /usr/lib/python2.5/logging/handlers.py, line 147, in shouldRollover self.stream.seek(0, 2) #due to non-posix-compliant Windows feature ValueError: I/O operation on closed file Does anyone have any ideas as to what I’m doing wrong here? Is this a known issue which has a neat little work around? Python makes no guarantees that it will tear down your objects before it tears down the library's objects (or the library itself). See e.g. http://www.python.org/doc/essays/cleanup/ (old and probably somewhat outdated, but you get the idea) I'd just put a try/except around it, and ignore any exceptions that may occur. /F -- http://mail.python.org/mailman/listinfo/python-list
Re: Logging in __del__()
On Jul 15, 1:51 pm, Robert Rawlins [EMAIL PROTECTED] wrote: Am I right in thinking that Python destroys instances of classes when it deems they are no longer needed? I shouldn't have to explicitly delete the classes, right? Python uses reference counting with a cycle detector, but the detector's behaviour is different if there are finalizers (__del__) - see http://www.python.org/doc/ext/refcounts.html Regards, Vinay Sajip -- http://mail.python.org/mailman/listinfo/python-list
