[Python-Dev] py3k: TypeError: object.__init__() takes no parameters

[Terry Reedy]

Nick Coghlan wrote:
> Terry Reedy wrote:

>> So I wonder whether the proper change might have been to remove
>> object.__init__.
> 
> That would have broken too much code, since a lot of immutable types
> rely on it (they only override __new__ and leave __init__ alone).

In what way do they depend on the equivalent of "def f(): pass"?
If, during the object creation process, "if hasattr(newob, '__init__'):" 
were added after calling cls.__new__ and before calling newob.__init__, 
what dependency would be left?

To repeat a previous comment, the doc sentence beginning "If a base 
class has an __init__() method," implies that it is intended to be 
possible for classes to not have an __init__ method.  Should the doc be 
changed.  Is this just a holdover from pre-object-class days?

> For more info, see Guido's checkin changing the behaviour and the
> associated tracker issue:
> http://svn.python.org/view?rev=54539&view=rev
> http://bugs.python.org/issue1683368

Ah yes.  In that thread I complained that

 >>> object.__init__.__doc__
'x.__init__(...) initializes x; see x.__class__.__doc__ for signature'

unchanged in 3.0) is uninformative.  Why cannot object.__init__.__doc__ 
tell the truth?

"object.__init__(self) takes no other args and does nothing"

The signature of a class as a callable is *not* the signature of its 
__init__ method!

In particular

 >>> object.__class__.__doc__
"type(object) -> the object's type\ntype(name, bases, dict) -> a new type"

(also unchanged in 3.0) is irrelevant and uninformative as to whether 
object.__init__ accepts (as it used to) or rejects (as it now does) args 
other than 'self'.

Terry Jan Reedy