Steven D'Aprano schrieb am 14.07.2015 um 06:54:
> On Tuesday 14 July 2015 14:45, Ben Finney wrote:
>> The Python reference says of a class ‘__new__’ method::
>>
>> object.__new__(cls[, ...])
>>
>> 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.
>
> This is correct. __new__ is a static method and you need to explicitly
> provide the cls argument:
And it needs to be that way in order to allow superclass calls in a
subclass's __new__ method:
class Super(object):
def __new__(cls):
return object.__new__(cls)
class Sub(Super):
def __new__(cls):
return Super.__new__(cls)
If it was a classmethod, it would receive the class you call it on as first
argument (i.e. "Super" and "object" above), not the class you want to
instantiate (i.e. "Sub" or "Super").
Stefan
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