228: Highlights

Smalltalk classes correspond to groups, and Smalltalk instances correspond to individuals.
Class definitions generally include instance variables, also known as member variables, fields, or slots.
If you want to define a simple class, with instance variables only, then click on that class's superclass in the class-hierarchy browser and instantiate the following pattern:
```
superclass name subclass: #class name 
  instanceVariableNames: 'instance variables' 
  classVariableNames: '' 
  poolDictionaries: '' 
```
If you want to create an instance of a class, then instantiate the following pattern:
```
class name new 
```
Setter and getter methods provide a route to instance-variable assignment and reference. Collectively, setters and getters are called accessors.
If you want to be able to assign an instance-variable value using a setter, then instantiate the following definition in the class-hierarchy browser:
```
variable name: aValue 
  ^variable name := aValue 
```
If you want to be able to refer to a instance-variable value using a getter, then instantiate the following definition in the class-hierarchy browser:
```
variable name 
  ^variable name 
```
You can define setter and getter methods for derived attributes.