Overriding list.__new__

[Terry Reedy]

"Michele Simionato" <mis6 at pitt.edu> wrote in message
news:2259b0e2.0307031246.6054693d at posting.google.com...
> Let me show first how does it work for tuples:
>
> >>> class MyTuple(tuple):
> ...     def __new__(cls,strng): # implicit conversion string of ints
=> tuple
> ...         return
super(MyTuple,cls).__new__(cls,map(int,strng.split()))
> >>> MyTuple('1 2')
> (1, 2)
>
> No wonder here, everything is fine. However, if I do the same for
> lists I get the following:

Values of immutable objects must be set when created, because they
cannot be changed thereafter.  Mutable objects can be initialized in
the __init__() method.  I suspect this is true of lists, so that
overriding __new__ for lists has no effect.

TJR