On 6 juin, 19:51, The Pythonista <[EMAIL PROTECTED]> wrote: > I've been wondering for a while about whether assigning to __class__ is > bad form or not. Specifically, I mean doing so when some other method of > implementing the functionality you're after is available (i.e. using an > adapter, or something like the strategy pattern). > > To give an example and a non-example of what I'm talking about, consider > the following recipes from the online Python Cookbook: > > Ring Buffer:http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/68429 > > In this case, I think the assignment to __class__ just obfuscates things, > and the example would be better coded as a single class. > > On the other hand, > > Fast copy of an object having a slow __init__ : http:// > aspn.activestate.com/ASPN/Cookbook/Python/Recipe/66507 > > This seems like a reasonable use case for assigning to __class__ (except > that it's already implemented in the 'new' module, but, read the Martelli- > bot's comments near the end of the recipe). I consider this a reasonable > use case for assigning to __class__, because, short of the 'new' module, > I don't see any other way to accomplish it. > > So, what is the opinion of the broader Python community?
My first opinion is that your formulation, ie "assigning *to* __class__" is perhaps a bit misleading. What you're talking about is rebinding the __class__ attribute, while, from your subject line, I thought you were talking about reassigning to (rebinding) a class attribute from the instance, ie : self.__class__.attrib = value. Now to the point: > Is code that > assigns to __class__ just clever trickiness to be avoided, or is it > sometimes a good thing? Both, definitively !-) Like most of Python's "advanced" features, it's nice to have it because it can easily solve problems that would otherwise be at best a PITA, but it's not something you use on a daily basis - nor without thinking twice. And obviously, there's no clear rule here, except good taste and common sense. Anyway, the mere fact that you're asking yourself if it's a good idea in such or such case is a probably a good indication that you'll find out by yourself the day you'll be tempted to use this trick whether it's a good or bad idea in this particular context. -- http://mail.python.org/mailman/listinfo/python-list
