overriding a tuple's __init__

[Andrew Dalke]

Simon Burton:
> >>> class pair(tuple):
> ...   def __init__(self,a,b):
> ...     tuple.__init__(self, (a,b) )

> What gives? (yes it works with a list, but i need immutable/hashable)

The problem is the immutability.  This one one of the
new changes in 2.3 I still don't fully understand, but I do
know the solution is __new__

>>> class pair(tuple):
...  def __new__(self, a, b):
...   return tuple((a, b))
...
>>>
>>> pair(2,3)
(2, 3)
>>> x=_
>>> type(x)
<type 'tuple'>
>>>

That should give you some pointers for additional searches.

                    Andrew
                    dalke at dalkescientific.com