Re: Don't use __slots__ (was Re: Problem of Readability of Python)
In article [EMAIL PROTECTED], Steven Bethard [EMAIL PROTECTED] wrote: Aahz wrote: In article [EMAIL PROTECTED], Steven Bethard [EMAIL PROTECTED] wrote: You can use __slots__ [...] Aaaugh! Don't use __slots__! Seriously, __slots__ are for wizards writing applications with huuuge numbers of object instances (like, millions of instances). You clipped me saying that __slots__ are for performance tweaks: You can use __slots__ to make objects consume less memory and have slightly better attribute-access performance. Classes for objects that need such performance tweaks should start like... I fully agree that __slots__ are for applications with huge numbers of instances. But if you have that situation, you really do want to be using __slots__. Well, then, just make sure to put big honking warnings up whenever you mention __slots__. ;-) -- Aahz ([EMAIL PROTECTED]) * http://www.pythoncraft.com/ The best way to get information on Usenet is not to ask a question, but to post the wrong information. -- http://mail.python.org/mailman/listinfo/python-list
Re: Don't use __slots__ (was Re: Problem of Readability of Python)
On Sun, 07 Oct 2007 21:27:31 -0700, Aahz wrote: In article [EMAIL PROTECTED], Steven Bethard [EMAIL PROTECTED] wrote: You can use __slots__ [...] Aaaugh! Don't use __slots__! Seriously, __slots__ are for wizards writing applications with huuuge numbers of object instances (like, millions of instances). For an extended thread about this, see http://groups.google.com/group/comp.lang.python/browse_thread/ thread/8775c70565fb4a65/0e25f368e23ab058 Well, I've read the thread, and I've read the thread it links to, and for the life of me I'm still no clearer as to why __slots__ shouldn't be used except that: 1 Aahz and Guido say __slots__ are teh suxxor; 2 rumour (?) has it that __slots__ won't make it into Python 3.0; 3 inheritance from classes using __slots__ doesn't inherit the slot- nature of the superclass. Point 1 is never to be lightly dismissed, but on the other hand Guido doesn't like reduce(), and I'm allergic to Cos I Said So arguments. History is full of things which were invented for one purpose being used for something else. So, that being the case, suppose I accept that using __slots__ is not the best way of solving the problem, and that people of the skill and experience of Guido and Aahz will roll their eyes and snicker at me. But is there actually anything *harmful* that can happen if I use __slots__? -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
Re: Don't use __slots__ (was Re: Problem of Readability of Python)
Steven D'Aprano wrote: On Sun, 07 Oct 2007 21:27:31 -0700, Aahz wrote: In article [EMAIL PROTECTED], Steven Bethard [EMAIL PROTECTED] wrote: You can use __slots__ [...] Aaaugh! Don't use __slots__! Seriously, __slots__ are for wizards writing applications with huuuge numbers of object instances (like, millions of instances). For an extended thread about this, see http://groups.google.com/group/comp.lang.python/browse_thread/ thread/8775c70565fb4a65/0e25f368e23ab058 Well, I've read the thread, and I've read the thread it links to, and for the life of me I'm still no clearer as to why __slots__ shouldn't be used except that: 1 Aahz and Guido say __slots__ are teh suxxor; 2 rumour (?) has it that __slots__ won't make it into Python 3.0; 3 inheritance from classes using __slots__ doesn't inherit the slot- nature of the superclass. Point 1 is never to be lightly dismissed, but on the other hand Guido doesn't like reduce(), and I'm allergic to Cos I Said So arguments. History is full of things which were invented for one purpose being used for something else. So, that being the case, suppose I accept that using __slots__ is not the best way of solving the problem, and that people of the skill and experience of Guido and Aahz will roll their eyes and snicker at me. But is there actually anything *harmful* that can happen if I use __slots__? Point 3 clearly is harmful. As is the fact that __slots__ gives you troubles if you e.g. pass objects to code that tries to set arbitrary attributes on an object. While this might be frowned upon, it can be useful in situations where you e.g. link GUI-code/objects with data-objects: instead of creating cumbersome, explicit mappings (as you have to in C/C++/Java) or wrappers, just set a well-named property. The question is: what does a slot buy you for this kind of problem? And while arguing with then I can't set an attribute I didn't want to be set is certainly possible, it ultimately leads to the darn static-vs-dynamic-discussion. Which we might spare us this time. Diez -- http://mail.python.org/mailman/listinfo/python-list
Re: Don't use __slots__ (was Re: Problem of Readability of Python)
On Mon, 08 Oct 2007 15:15:36 +0200, Diez B. Roggisch wrote: Well, I've read the thread, and I've read the thread it links to, and for the life of me I'm still no clearer as to why __slots__ shouldn't be used except that: 1 Aahz and Guido say __slots__ are teh suxxor; 2 rumour (?) has it that __slots__ won't make it into Python 3.0; 3 inheritance from classes using __slots__ doesn't inherit the slot- nature of the superclass. Point 1 is never to be lightly dismissed, but on the other hand Guido doesn't like reduce(), and I'm allergic to Cos I Said So arguments. History is full of things which were invented for one purpose being used for something else. So, that being the case, suppose I accept that using __slots__ is not the best way of solving the problem, and that people of the skill and experience of Guido and Aahz will roll their eyes and snicker at me. But is there actually anything *harmful* that can happen if I use __slots__? Point 3 clearly is harmful. No, it is DIFFERENT, not harmful. At worst, it's a gotcha -- a really well-documented gotcha. As is the fact that __slots__ gives you troubles if you e.g. pass objects to code that tries to set arbitrary attributes on an object. You mean like this? x = 1 x.label = foo Traceback (most recent call last): File stdin, line 1, in module AttributeError: 'int' object has no attribute 'label' I guess that means ints and floats and strings and tuples and lists are all harmful too, yes? The question is: what does a slot buy you for this kind of problem? Simplicity and explicitness. -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
Re: Don't use __slots__ (was Re: Problem of Readability of Python)
Steven D'Aprano wrote: On Mon, 08 Oct 2007 15:15:36 +0200, Diez B. Roggisch wrote: Well, I've read the thread, and I've read the thread it links to, and for the life of me I'm still no clearer as to why __slots__ shouldn't be used except that: 1 Aahz and Guido say __slots__ are teh suxxor; 2 rumour (?) has it that __slots__ won't make it into Python 3.0; 3 inheritance from classes using __slots__ doesn't inherit the slot- nature of the superclass. Point 1 is never to be lightly dismissed, but on the other hand Guido doesn't like reduce(), and I'm allergic to Cos I Said So arguments. History is full of things which were invented for one purpose being used for something else. So, that being the case, suppose I accept that using __slots__ is not the best way of solving the problem, and that people of the skill and experience of Guido and Aahz will roll their eyes and snicker at me. But is there actually anything *harmful* that can happen if I use __slots__? Point 3 clearly is harmful. No, it is DIFFERENT, not harmful. At worst, it's a gotcha -- a really well-documented gotcha. To the casual observer? I doubt it. I wasn't aware of that until a recent discussion about slots. But then, I've so far _never_ felt the need to use them... As is the fact that __slots__ gives you troubles if you e.g. pass objects to code that tries to set arbitrary attributes on an object. You mean like this? x = 1 x.label = foo Traceback (most recent call last): File stdin, line 1, in module AttributeError: 'int' object has no attribute 'label' I guess that means ints and floats and strings and tuples and lists are all harmful too, yes? You are very well aware that I was talking about complex objects. And I didn't say that they are harmful, but that using __slots__ to constrain object attribute will lead to surprising results here in comparison to the usual behavior. And with usual I mean most-of-the-classes-work-that-way. Which might be considered as reason to _not_ do it. But you are free to limit yourself, be my guest. The question is: what does a slot buy you for this kind of problem? Simplicity and explicitness. Where is that more simple? Additional notation that will lead to runtime-errors, the same way misspelled attribute-names do? And yes, it is more explicit. As are interfaces, and type declarations. Diez -- http://mail.python.org/mailman/listinfo/python-list
Re: Don't use __slots__ (was Re: Problem of Readability of Python)
Aahz wrote: In article [EMAIL PROTECTED], Steven Bethard [EMAIL PROTECTED] wrote: You can use __slots__ [...] Aaaugh! Don't use __slots__! Seriously, __slots__ are for wizards writing applications with huuuge numbers of object instances (like, millions of instances). You clipped me saying that __slots__ are for performance tweaks: You can use __slots__ to make objects consume less memory and have slightly better attribute-access performance. Classes for objects that need such performance tweaks should start like... I fully agree that __slots__ are for applications with huge numbers of instances. But if you have that situation, you really do want to be using __slots__. STeVe -- http://mail.python.org/mailman/listinfo/python-list
Don't use __slots__ (was Re: Problem of Readability of Python)
In article [EMAIL PROTECTED], Steven Bethard [EMAIL PROTECTED] wrote: You can use __slots__ [...] Aaaugh! Don't use __slots__! Seriously, __slots__ are for wizards writing applications with huuuge numbers of object instances (like, millions of instances). For an extended thread about this, see http://groups.google.com/group/comp.lang.python/browse_thread/thread/8775c70565fb4a65/0e25f368e23ab058 -- Aahz ([EMAIL PROTECTED]) * http://www.pythoncraft.com/ The best way to get information on Usenet is not to ask a question, but to post the wrong information. -- http://mail.python.org/mailman/listinfo/python-list
Re: Don't use __slots__ (was Re: Problem of Readability of Python)
On Oct 8, 12:27 am, [EMAIL PROTECTED] (Aahz) wrote: Aaaugh! Don't use __slots__! +1 QOTW ;) Michele Simionato -- http://mail.python.org/mailman/listinfo/python-list
