[Tutor] How to set variables inside a class()

[eryksun]

On Tue, Nov 26, 2013 at 6:13 AM, Dominik George <nik at naturalnet.de> wrote:
> Now when zou instantiate the class, then the dictionary is copied to the
> instance (carying references to the same data inside it, mind you!),

Perhaps the above is just a simple mistake of wording, but to be
clear, the class dict isn't copied to an instance.

    >>> class Animal(object): # extend object!!!
    ...     flag = True
    ...

    >>> a = Animal()
    >>> Animal.__dict__['flag']
    True
    >>> a.__dict__ # or vars(a)
    {}

The generic object __getattribute__ (tp_getattro slot in the C
implementation) looks in the dicts of the type and its bases, i.e. the
types in the MRO:

    >>> class Dog(Animal):
    ...     flag = False
    ...
    >>> Dog.__mro__
    (<class '__main__.Dog'>, <class '__main__.Animal'>,
     <type 'object'>)

The order of possible return values is as follows:

* a data-descriptor class attribute (e.g. a property):
  return the result of its __get__ method
* an instance attribute
* a non-data descriptor class attribute (e.g. a function):
  return the result of its __get__ method
  (e.g. return a bound instance method)
* a non-descriptor class attribute

If the attribute isn't found it raises an AttributeError. If you
implement the fallback __getattr__ method, the AttributeError is
swallowed and the onus is on you.