Notes on Semantics of Smalltalk

.Status PREDRAFT

A Smalltalk shares a class with similar objects

class::objects -> classes.
instances:: classes-> @classes= /class.
is_instance_of::@(objects, classes)={ (x,c) | c = class(x) }.
Each object has special distinguishing values that are called its instance variable:
instance_variables::(objects><variables)<>->values.
Classes define what set of instance variables are valid for their objects.
Classes also determine the way that their objects react to messages. They assoicate each message selector with a method for handling it. The set of possible messages for a class is called its protocol:
protocol::(class><selector)<>->method.
Each method has
1. arguments
2. local variables
3. a sequence of steps
A message has a selector and an array of arguments;
messages::selector >< #objects
Sending a message to an object produces another object:
____send______
|
| x?:objects
| m?:messages
|
| result':objects
|
|--------------------
|
| ...
|_____________