Department of
Computer Science

CS 420/520 Object-Oriented Programming

What is Squeak

Squeak VM Download

Squeak Sources

The Class Image

Directory

What is Squeak?

Squeak is a modern, open source, highly portable, fast and full-featured implementation of the powerful Smalltalk programming language and environment.

When Smalltalk was created more than 25 years ago it defined the term object orientation and is the first language in which everything is built from objects. Smalltalk is deeply inspired by ideas from especially Simula, Sketchpad and Lisp and even today Smalltalk sets the bar for object-oriented dynamically typed interactive languages and environments.

You may be familiar with other open-source languages like Ruby or Python, but Squeak takes these concepts much, much further offering a true uniform fully-reflective environment, where everything is a real live object.

To run Squeak you will need four files: a Virtual Machine, a sources file, and the image/changes file pair (provided by me for this class).

For more information, see the Squeak website.

Running Squeak on the CAT-supported Windows Computers

The virtual machine is already installed, but has to be "added to" your account. The CAT writes thusly:

Open the start menu and choose "Run..."

At the prompt type P:\Programs\Squeak\add package.cmd

Assuming the script finds nothing wrong hit any key to close the window when it finishes.

You can now run a Squeak image by double-clicking on the image file.

Once you have run "add package.cmd" you will have a N:\squeak folder.

Unzip the class image into your squeak folder, and you should be set to go.

Squeak Virtual Machine Download

• If you are using a computer in the CS lab at PSU, the Squeak VM should already be installed on both Windows and Ubuntu Linux.

• To install on your personal machine, download the VM here: Unix (including MacOS X), Windows and others

Put this whereever your OS likes you to put executables.

Make a working directory for yourself

PSU Class image

• This is an image that I have prepared for this class. Please use it! Put it in your working directory and unzip it. It consists of two files: a .image file and a .changes file. You will need both. Make a virgin backup copy now! These files will change as you work.

Squeak Sources

• You will need the "sources" file. This a binary file, and is the same on all platforms. It is zipped to discourage your download agent from treatiung it as a text file. Without this file, Squeak will complain that it can't find the sources, and you won't be able to browse the source code of the standard system classes. Unzip this file and put it in your working directory. You can also put it in the same directory as the VM.

  You will find the sources file in the zip package with the class image, or you can get it where you got your VM.

Try it Out

• Launch Squeak! Depeinding on your User Interface, double-click on the image file, frag the image file into the VM, or change to your working direcvtory and type <path to VM> <image file>.

Directory of more Squeak stuff

• As the quarter progresses, I'll put stuff that we find useful in this directory.