__new__ does not call __init__ as described in descrintro.html (WAS: Can __new__ prevent __init__ from being called?)

[Steven Bethard]

Felix Wiemann wrote:
 > Steven Bethard wrote:
 >>     http://www.python.org/2.2.3/descrintro.html#__new__
 >
[snip]
 >
 > I'm just seeing that the web page says:
 >
 > | If you return an existing object, the constructor call will still
 > | call its __init__ method. If you return an object of a different
 > | class, its __init__ method will be called.
 >
 > However, the latter doesn't seem to be true, or am I missing
 > something?
 >
 >>>>class A(object):
 > ...   def __init__(self):
 > ...     print 'Init of A.'
 > ...
 >
 >>>>instance = A()
 > Init of A.
 >
 >>>>class B(object):
 > ...   def __new__(self):
 > ...     return instance
 > ...   def __init__(self):
 > ...     print 'Init of B.'
 > ...
 >
 >>>>B()  # <--------- A's __init__ is *not* called.
 > <__main__.A object at 0x4062424c>
 >
 >>>>instance = object.__new__(B)
 >>>>B()  # <--------- B's __init__ is called
 > Init of B.
 > <__main__.B object at 0x406243ec>
 >
 > So there seems to be some type-checking in type.__call__.

Yeah, I saw the same thing in playing around with this.  Don't know what 
to make of it.  I wonder if we should file a documentation bug?  I can't 
find __new__ explained anywhere in the Language Reference.  Can 
documentation bugs be filed for descrintro.html?

STeVe