[Tutor] __new__ over __init__

[Peter Otten]

Payal wrote:

> Can someone please give a very simple example of using __new__ wherein
> __init__ cannot be used?

Subclasses of immutable types, e. g. tuple:

>>> class A(tuple):
...     def __init__(self, a, b):
...             pass
...
>>> a = A(1,2)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: tuple() takes at most 1 argument (2 given)
>>> class A(tuple):
...     def __new__(cls, a, b):
...             return tuple.__new__(cls, (a, b))
...
>>> A(1, 2)
(1, 2)
>>> type(_)
<class '__main__.A'>

Peter