Day 9 - Classes

Class organization

A class should begin with a list of variables, public static constants should come first; then private static variables followed by private instance variables. There is seldom a good reason to have public variables
Public functions should follow the list of variables. We want to put the private utilities called by a public function right after the public function itself

Encapsulation

We like to keep our variables and utility functions private but sometimes we need to make them protected so that it can be accessed by a test

Classes should be small

With functions we measured size by counting physical lines. With classes we count responsibilities

Single responsibility principle

Cohesion

Classes should have a small number of instance variables. In general the more variables a method manipulates the more cohesive that method is to its class

Organizing for change

In a clean system we organize our classes so as to reduce the risk of change