interactive help on the base object

Terry Reedy tjreedy at udel.edu
Mon Dec 9 06:00:53 CET 2013


On 12/8/2013 8:43 PM, Mark Lawrence wrote:
> On 09/12/2013 00:45, Denis McMahon wrote:
>> On Sun, 08 Dec 2013 23:48:57 +0000, Mark Lawrence wrote:
>>
>>>>>   >>> help(object)
>>>>> Help on class object in module builtins:
>>>>>
>>>>> class object
>>>>>    |  The most base type
>>
>>
>>>> '''The default top superclass for all Python classes.
>>>> Its methods are inherited by all classes unless overriden.
>>>> '''

I said 'top' instead of 'bottom' or 'base' to loosen up thinking a bit. 
I did not expect Mark to make a mound out of that flip.

>>> Terry's suggestion above remains odds on favourite on the grounds that
>>> there have been no other suggestions.  I'll give it another day, then
>>> raise a tracker issue, unless the overwhelming smell of pot that has
>>> been drifting around this thread knocks me unconscious.
>>
>> """ The root class for all Python classes. Its methods are inherited by
>> all classes unless overriden. """

'Root' is even better, since it does not depend on whether a tree is 
drawn up or down. Thanks.

> Thanks Denis, you've reminded me why I asked in the first place.  What
> methods, if any does it provide?

Good question.
 >>> dir(object)
['__class__', '__delattr__', '__dir__', '__doc__', '__eq__', 
'__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', 
'__init__', '__le__', '__lt__', '__ne__', '__new__', '__reduce__', 
'__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', 
'__subclasshook__']

>  Are they all abstract? etc???

No.

> Personally I'm not really interested, but a newbie might well be and
> hence might wonder what the hell is going on.

For everything else, help lists the special name methods directly 
associated with the object, along with docstrings.

 >>> help(C)
Help on class C in module __main__:

class C(builtins.object)
  |  Data descriptors defined here:
  |
  |  __dict__
  |      dictionary for instance variables (if defined)
  |
  |  __weakref__
  |      list of weak references to the object (if defined)

I think help should do the same for object

 >>> object.__hash__.__doc__
'x.__hash__() <==> hash(x)'

is equivalent to

  | __abs__(...)
  |      x.__abs__() <==> abs(x)

etc printed for help(int)

The fact that __dict__ does not exist for object but is only added for 
subclasses explains why one must subclass object to get instances that 
allow attributes.

 >>> o = object()
 >>> o.a = 1
Traceback (most recent call last):
   File "<pyshell#8>", line 1, in <module>
     o.a = 1
AttributeError: 'object' object has no attribute 'a'
 >>> c = C()
 >>> c.a=1

> If and only if the
> situation can be improved I'll raise an issue

I think it can be. If you prefer me to open the issue, say so.
We should look for existing issues, and closed issues that rejected change.

-- 
Terry Jan Reedy




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