Clean Code in Python

Data descriptors

Now, let's look at the difference of using a data descriptor. For this, we are going to create another simple descriptor that implements the __set__ method:

class DataDescriptor:    def __get__(self, instance, owner):        if instance is None:            return self        return 42    def __set__(self, instance, value):        logger.debug("setting %s.descriptor to %s", instance, value)        instance.__dict__["descriptor"] = valueclass ClientClass:    descriptor = DataDescriptor()

Let's see what the value of the descriptor returns:

>>> client = ClientClass()>>> client.descriptor42

Now, let's try to change this value to something else, and see what it returns instead:

>>> client.descriptor = 99>>> client.descriptor42

The value returned by the descriptor didn't ...