Basic misunderstanding on object creation

[andrew cooke]

On Wednesday, 13 May 2015 13:37:23 UTC-3, Terry Reedy  wrote:
> On 5/13/2015 9:25 AM, andrew cooke wrote:
> 
> > The following code worked on Python 3.2, but no longer works in 3.4.
> 
> Bugfixes break code that depends on buggy behavior. See
> https://bugs.python.org/issue1683368
> Your code also fails in 2.7.9 if you inherit Foo from object.
> The exact error messages changed for 3.4 in
> https://bugs.python.org/issue7963
> 
>  > Did something change,
> 
> Obviously yes.

thanks, but why does someone on this group always have to be a dick and make some smart-assed comment like this?

>  > or have I always been doing something dumb?
> 
> You were depending on behavior of object that Guido decided was buggy.
> 
> I found the tracker issue by looking for 'object' in the Core and 
> Builtins sections of the changelog one can access from What's New, first 
> paragraph (using Highlight All in Firefox).
> 
> >>>> class Foo:
> > ...     def __new__(cls, *args, **kargs):
> > ...         print('new', args, kargs)
> > ...         super().__new__(cls, *args, **kargs)
> > ...
> >>>> class Bar(Foo):
> > ...     def __init__(self, a):
> > ...         print('init', a)
> > ...
> >>>> Bar(1)
> > new (1,) {}
> > Traceback (most recent call last):
> >    File "<stdin>", line 1, in <module>
> >    File "<stdin>", line 4, in __new__
> > TypeError: object() takes no parameters
> >
> > What I was expecting to happen (and what happens in 3.2) is that the object.__new__ method passes the argument to the __init__ of the subclass.
> 
> -- 
> Terry Jan Reedy