err, that should be super(TheClass, cls), otherwise you make your class unsubclassable.
On 3 November 2010 10:34, mark florisson <[email protected]> wrote: > > > On 3 November 2010 07:15, Robert Bradshaw <[email protected]>wrote: > >> On Tue, Nov 2, 2010 at 10:59 PM, Stefan Behnel <[email protected]> >> wrote: >> > Robert Bradshaw, 02.11.2010 23:21: >> >> On Tue, Nov 2, 2010 at 3:11 PM, Vitja Makarov wrote: >> >>> http://docs.python.org/reference/datamodel.html#basic-customization >> >>> >> >>> """Called to create a new instance of class cls. __new__() is a static >> >>> method (special-cased so you need not declare it as such) that takes >> >>> the class of which an instance was requested as its first argument. >> >>> The remaining arguments are those passed to the object constructor >> >>> expression (the call to the class). The return value of __new__() >> >>> should be the new object instance (usually an instance of cls).""" >> >> >> >> I was actually thinking about cdef classes, where __new__ is much more >> >> subtle. I didn't realize it was a static method that takes the class >> >> as a first argument rather than just a class method. >> > >> > It needs to be to support inheritance. You usually call the __new__ >> method >> > of the superclass to create the instance that you return. So you must be >> > able to pass the required class through the hierarchy explicitly. >> >> Good point, I hadn't thought about that. >> >> - Robert >> _______________________________________________ >> Cython-dev mailing list >> [email protected] >> http://codespeak.net/mailman/listinfo/cython-dev >> > > It could also work with a classmethod, because you'd be using super(cls, > cls).__new__(), which also ensures that the subclass is passed as the first > argument to __new__ in superclasses. Of course, type(TheClass).__call__ will > pass the TheClass as the first argument, so if you make __new__ a > classmethod it will need to take the class as two arguments. >
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