setattr and getattr : Attribute « Class « Python Tutorial

# __getattribute__(self, name): Automatically called when the attribute name is accessed. 
# __getattr__(self, name): Automatically called when the attribute name is accessed and the object has no such attribute.
# __setattr__(self, name, value): Automatically called when an attempt is made to bind the attribute name to value.
# __delattr__(self, name): Automatically called when an attempt is made to delete the attribute name.


class Rectangle:
    def __init__(self):
        self.width = 0
        self.height = 0
    def __setattr__(self, name, value):
        if name == 'size':
            self.width, self.height = value
        else:
            self.__dict__[name] = value
    def __getattr__(self, name):
        if name == 'size':
            return self.width, self.height
        else:
            raise AttributeError

11.2.Attribute
	11.2.1.	setattr and getattr
	11.2.2.	Attribute Reference
	11.2.3.	Modifying Class Attributes
	11.2.4.	Attributes are values associated with the object.
	11.2.5.	Instance Attributes versus Class Attributes
	11.2.6.	Use Caution When Accessing Class Attribute with Instance
	11.2.7.	Class Attributes More Persistent
	11.2.8.	Let us make our example more useful by giving P some attributes
	11.2.9.	Simple Attribute Lookup Example
	11.2.10.	hasattr(), getattr(), setattr(), delattr()
	11.2.11.	Class Employee with class attribute count.
	11.2.12.	Class that defines method __getattribute__ and __getattr__
	11.2.13.	Attach attributes to the class by assigning names to it outside of the original class