GNU SmallTalk 1.1

        Source Language:        C
        Built:                  VMS V5.4


This directory tree contains GNU Smalltalk 1.1 modified for VMS.

GNU Smalltalk is an implementation of the Blue Book (Smalltalk-80: The
Language and its Implementation, by Adele Goldberg and David Robson).

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.  The object's data representation
capabilities and the operations available on the object are
``inseparable''; the set of things that you can do with an object is defined
precisely by the set of operations, which Smalltalk calls 'methods',
that are available for that object.  You cannot even examine the
contents of an object from the outside.  To an outsider, the object is a
black box that has some state and some operations available, but that's
all you know.

In the Smalltalk language, everything is an object.  This includes
variables, executable procedures (methods), stack frames (called method
contexts or block contexts), etc.  Each object is an 'instance' of a
'class'.  A class can be thought of as a datatype and the set of
functions that operate on that datatype.  An instance is a particular
variable of that datatype.

When you want to perform an operation on an object, you send it a 
'message', and the object performs that message.  For example, to 
print an object, you'd send it the message 'print', thus:

randomObject print


The message that you send is actually the name of a method (procedure) to 
invoke.  When you send a message to an object, Smalltalk tries to find a
method that's defined for that type of object.  It first looks in the
object's class for a method that matches.  If none is found there, it looks
in the object's parent class, then the grandparent class, and so on.  At
the top of the class structure is a class called Object, which has no parent.
If the method is not found by the time that the searching gets to the methods
of class Object, an error occurs.  This error is signalled by sending the
original object a 'doesNotUnderstand:' message, which, if not intercepted by
the object's class or any parent class, will be handled by Object itself by
reporting the error to the user and printing a backtrace of the methods
that had been invoked at the time the error occurred.

For further information see [mits.smalltalk.smalltalk_1.1]mst.texinfo
(which is designed to be viewed with Emacs).

To run Smalltalk, execute symbols.com :-

        $ @[mits.smalltalk]symbols

Smalltalk may then be invoked in two ways :-

        Line mode - 
                                $ mst

        DECwindows mode - 
                                $ xmst

If you need to rebuild the image file :-

        $ set default smalltalk_image:
        $ delete mst.im;*
        $ mst build_image.st


[MITS.SMALLTALK.LIB]

        This is the directory where I keep the image file.  It also
        contains a few methods which I have written, plus the
        definitions for the X-Window interface.

[MITS.SMALLTALK.VOICE]

        This is a start at interfacing DECtalk to Smalltalk.  It
        doesn't work particularly well, but you're welcome to it.

[MITS.SMALLTALK.XW]

        This is a simple DECwindows interface for Smalltalk.  To
        execute a Smalltalk command, select the text using MB1, and
        invoke using MB3.  Alternatively, use the pop-up menu with
        MB2.  This still has a few bugs, but is generally a whole lot
        better than line mode.


        Author: Steve Byrne


Alistair Grant

Internet:     alistair@mits.com.au    PSI Mail:     psi%0505238730004::alistair
Alternate:    alistair%mits.com.au@ucsvc.ucs.unimelb.edu.au
              grant@decus.com.au