smalltalk tutorial for beginners

What This Manual Presents

This document provides a tutorial introduction to theSmalltalk language in general, and the GNU Smalltalk implementation inparticular. It does not provide exhaustive coverage of every feature of the language and its libraries;instead, it attempts to introduce a critical mass of ideasand techniques to get the Smalltalk novice moving in theright dire...

Who This Manual Is Written For

This manual assumes that the reader is acquainted with the basics ofcomputer science, and has reasonable proficiency with a procedural languagesuch as C. It also assumes that the reader is already familiarwith the usual janitorial tasks associated with programming - editing,moving files, and so forth.

Getting Started

1.1. Starting up Smalltalk

Using Some of The Smalltalk Classes

This chapter has examples which need a place to holdthe objects they create. The following line creates such aplace; for now, treat it as magic. At the end of the chapter we willrevisit it with an explanation. Type in:

The Smalltalk Class Hierarchy

When programming in Smalltalk, you sometimes need tocreate new kinds of objects, and define what various messages will do tothese objects. In the next chapter we will create some new classes, but first we need to understand howSmalltalk organizes the types and objects it contains.Because this is a pure "concept" chapter, without any actualSmalltalk...

Creating A New Class of Objects

With the basic techniques presented in the precedingchapters, we're ready do our first real Smalltalk program.In this chapter we will construct three new types of objects(known as "classes"), using the Smalltalk technique ofinheritance to tie the classes together, create new objectsbelonging to these classes (known as creating instancesofthe class)...

Two Subclasses For The Account Class

This chapter continues from the previous chapter indemonstrating how one creates classes and subclasses in Smalltalk. In thischapter we will create two special subclasses of Account,known as Checking and Savings. We will continueto inherit the capabilities of Account, but willtailor the two kinds of objects to better manage particular kinds ofaccou...

Code Blocks

The Account/Saving/Checkingexample from the last chapter has several deficiencies. It has no record ofthe checks and their values. Worse, it allows you to write a check whenthere are no more checks - the Integer value for the number of checks willjust calmly go negative! To fix these problems we will need to introducemore sophisticated control stru...

Code Blocks, Part Two

In the last chapter, we looked at how code blocks couldbe used to build conditional expressions, and how you could iterate acrossall entries in a collection. We built our own code blocks, and handed them offfor use by system objects. But there is nothing magic about invoking codeblocks; your own code will often need to do so. This chapter will show...

What is Smalltalk programming language?

The Smalltalk programming language is an object oriented programming language. This means, for one thing, that when programming you are thinking of not only the data that an object contains, but also of the operations available on that object.

What can be obtained with Smalltalk in this novel way?

An example of what can be obtained with Smalltalk in this novel way can be found in Section “Class reference” in the gnu Smalltalk Library Reference. That part of the manual is entirely generated by a Smalltalk program, starting from the source code for the class libraries distributed together with the system. 5 1 Using gnu Smalltalk

How do I start up the Smalltalk interactor?

To start up the Smalltalk interactor, you must be running gnu Emacs and in a buffer that’s in Smalltalk mode. Then, if you type C-c m. A second window will appear with gnu Smalltalk running in it. This window is in most respects like a Shell mode window.

How does Smalltalk organize its classes?

Smalltalk organizes all of its classes as a tree hierarchy. At the very top of this hierarchy is class Object. Following somewhere below it are more specific classes, such as the ones we’ve worked with—strings, integers, arrays, and so forth.