Introduction to OOP Chapter 23: Object Interconnections : next previous audio real text

Rewritten in terms of messages

Law of Demeter (weak form). Inside a method, it is only permitted to access or send messages to the following objects:

The arguments associated with the method being executed (including the self object).

Instance variables for the receiver of the method.

Global variables.

Temporary variables created inside the method.
Intro OOP, Chapter 23, Slide 15

The strong form eliminates global variables and inherited data fields.