Comments on: Python Gotchas 1: __del__ is not the opposite of __init__ http://www.algorithm.co.il/blogs/programming/python-gotchas-1-__del__-is-not-the-opposite-of-__init__/ Algorithms, for the heck of it Tue, 21 Jun 2011 21:07:08 +0000 hourly 1 http://wordpress.org/?v=3.1.3 By: B.Moore http://www.algorithm.co.il/blogs/programming/python-gotchas-1-__del__-is-not-the-opposite-of-__init__/#comment-268 B.Moore Thu, 14 Jan 2010 23:40:55 +0000 http://www.algorithm.co.il/blogs/?p=438#comment-268 It seems to me that the __del__ function must have a purpose and be necessary, otherwise why would the people who maintain and develop python keep the function around. I encountered this issue today and thanks to this article I resolved my problem. I realize now the proper way to use the __del__ deconstructor would have been to initialize all of the properties that I would be affecting on the first lines in the __init__ constructor. If I were a better coder and followed the most primitive standard of declaring and initializing variables first and at the top of my code I would't have seen this issue at all. Anyway good post and great commentary from everyone ;-) It seems to me that the __del__ function must have a purpose and be necessary, otherwise why would the people who maintain and develop python keep the function around.

I encountered this issue today and thanks to this article I resolved my problem. I realize now the proper way to use the __del__ deconstructor would have been to initialize all of the properties that I would be affecting on the first lines in the __init__ constructor.

If I were a better coder and followed the most primitive standard of declaring and initializing variables first and at the top of my code I would’t have seen this issue at all.

Anyway good post and great commentary from everyone ;-)

]]> By: Dormar http://www.algorithm.co.il/blogs/programming/python-gotchas-1-__del__-is-not-the-opposite-of-__init__/#comment-267 Dormar Tue, 27 Oct 2009 20:55:45 +0000 http://www.algorithm.co.il/blogs/?p=438#comment-267 Couldn't stress enough how much __del__ is unnecessary in most cases. 95% of python OO code I CR has unnecessary and possibly buggy __del__s. And not to even BEGIN talking about reference cycles and the problem you have with __del__'s in that case. Anyway - would love if you stress about it in a post :) Couldn’t stress enough how much __del__ is unnecessary in most cases.
95% of python OO code I CR has unnecessary and possibly buggy __del__s.
And not to even BEGIN talking about reference cycles and the problem you have with __del__’s in that case.
Anyway – would love if you stress about it in a post :)

]]> By: nirs http://www.algorithm.co.il/blogs/programming/python-gotchas-1-__del__-is-not-the-opposite-of-__init__/#comment-266 nirs Thu, 22 Oct 2009 21:09:46 +0000 http://www.algorithm.co.il/blogs/?p=438#comment-266 Good idea about class attributes here - it can clean up lot of code and even save lot of uninteresting __init__ implementations. Good idea about class attributes here – it can clean up lot of code and even save lot of uninteresting __init__ implementations.

]]> By: rmn http://www.algorithm.co.il/blogs/programming/python-gotchas-1-__del__-is-not-the-opposite-of-__init__/#comment-265 rmn Thu, 22 Oct 2009 16:38:28 +0000 http://www.algorithm.co.il/blogs/?p=438#comment-265 nice one, it actually makes sense - and important to know :) nice one, it actually makes sense – and important to know :)

]]> By: Shai http://www.algorithm.co.il/blogs/programming/python-gotchas-1-__del__-is-not-the-opposite-of-__init__/#comment-264 Shai Thu, 22 Oct 2009 09:31:28 +0000 http://www.algorithm.co.il/blogs/?p=438#comment-264 @nirs: You really can't be sure __init__ runs through anything. The exception that caused it to exit in mid-execution could have been KeyboardInterrupt. If you want defaults, they are better defined as class attributes, so that they're available to any instance; but better yet, is to do what the post says, and avoid __del__. @nirs:

You really can’t be sure __init__ runs through anything. The exception that caused it to exit in mid-execution could have been KeyboardInterrupt. If you want defaults, they are better defined as class attributes, so that they’re available to any instance; but better yet, is to do what the post says, and avoid __del__.

]]> By: nirs http://www.algorithm.co.il/blogs/programming/python-gotchas-1-__del__-is-not-the-opposite-of-__init__/#comment-263 nirs Tue, 20 Oct 2009 20:17:56 +0000 http://www.algorithm.co.il/blogs/?p=438#comment-263 It is best to either define all variables in __init__ with a default value before doing anything else, or in other methods, use getattr(self, 'name') when accessing attributes, to avoid attribute errors. It is best to either define all variables in __init__ with a default value before doing anything else, or in other methods, use getattr(self, ‘name’) when accessing attributes, to avoid attribute errors.

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