[Tutor] class variables

[eryksun]

On Fri, Dec 20, 2013 at 5:20 AM, Alan Gauld <alan.gauld at btinternet.com> wrote:
>
> Similarly if you have a name defined within the instance it will use that if
> not it will look in the class.

An instance can generally shadow class attributes, except properties
and other data descriptors defined by the class are given precedence
when looking up attributes:

    >>> instance = Class()
    >>> Class.pi = property(lambda s: 3.14)

    >>> instance.pi
    3.14
    >>> instance.pi = 4
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    AttributeError: can't set attribute

The property is used even if you manually assign pi in the instance dict:

    >>> vars(instance)['pi'] = 4
    >>> vars(instance)
    {'pi': 4}
    >>> instance.pi
    3.14