Modify arguments between __new__ and __init__

[Arnaud Delobelle]

On Dec 23, 5:03 am, Steven D'Aprano <st... at REMOVE-THIS-
cybersource.com.au> wrote:
> When you call a new-style class, the __new__ method is called with the
> user-supplied arguments, followed by the __init__ method with the same
> arguments.
>
> I would like to modify the arguments after the __new__ method is called
> but before the __init__ method, somewhat like this:
>
> >>> class Spam(object):
>
> ...     def __new__(cls, *args):
> ...             print "__new__", args
> ...             x = object.__new__(cls)
> ...             args = ['spam spam spam']
> ...             return x
> ...     def __init__(self, *args):
> ...             print "__init__", args  # hope to get 'spam spam spam'
> ...             return None
>
> but naturally it doesn't work:
>
> >>> s = Spam('spam and eggs', 'tomato', 'beans are off')
>
> __new__ ('spam and eggs', 'tomato', 'beans are off')
> __init__ ('spam and eggs', 'tomato', 'beans are off')
>
> Is there any way to do this, or am I all outta luck?
>
> --
> Steven

The ususal way is to override the __call__ method of the metaclass.

HTH

--
Arnaud