Smalltalk-80 as an Ada software environment

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2 total messages Started by Steven D. Litvintchouk Wed, 27 Aug 1986 01:27

#314

Author: Steven D. Litvintchouk
Date: Wed, 27 Aug 1986 01:27

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We at MITRE Corp.  have been looking into using the Smalltalk-80
programming environment as a software engineering environment to
support the development of real-time software systems to be
implemented in the Ada programming language.  (We in the U.S.
aerospace industry must deliver software in Ada, not Smalltalk.)  But
Smalltalk-80 provides a wonderfully user-extensible environment that
can do such things as:

1.  windowing, word processing, other mundane things (Question:  can
any Smalltalk-80 system, such as PS on Sun workstations, invoke tools
from the host operating system like Ada compilers?)

2.  Simulation/modelling/rapid prototyping of software systems that
are ultimately to be implemented in Ada

3.  Software reusability, by taking a Smalltalk class hierarchy and
	constructing its Ada equivalent (using Ada
	packages and compilation order semantics).  (You would 
	build a prototype/model class hierarchy in Smalltalk, and
	after modelling/simulation convinced you it was OK, you would
	then transliterate it to the corresponding Ada equivalent
	for the final product.)

4.  Research into Ada software performance.  The Ada programming
language includes facilities for multitasking, interrupt handling,
dynamic storage allocation/deallocation, etc.  Every Ada compiler
comes with a runtime library capable of doing such things.  We would
like to create a behavioral model (in Smalltalk) of a hypothetical,
generalized, instrumented, Ada runtime library, in order to learn
about the state of the art in runtime support for Ada multitasking and
storage management.

I plan to be at OOPSLA '86.  If anyone out there is also interested in
such "real-world" software engineering applications of Smalltalk,
please let me know; perhaps we could get together at OOPSLA and
compare notes.  Thanx very much in advance!!!


Steven Litvintchouk
MITRE Corporation
Burlington Road
Bedford, MA  01730

Fone:  (617)271-7753
ARPA:  sdl@mitre-bedford
UUCP:  ...{cbosgd,decvax,genrad,ll-xn,philabs,security,utzoo}!linus!sdl

Re: Smalltalk-80 as an Ada software env

#330

Author: johnson
Date: Mon, 01 Sep 1986 14:23

18 lines
1531 bytes

It is actually easy to simulate (in Ada) having a subclass redefine a
superclass's method.  Each class is simulated by a separate package
and the package for a subclass contains a procedure for each method
defined in the superclass unless the method was redefined in the
subclass.  Thus, the Ada code contains no trace of the class hierarchy.

The hard part of simulating Smalltalk in Ada is when the class of an
object is not known.  For example, the collection of subviews of a
view contains objects of many classes, each of which can have a
separate definition of "display" (actually, displayView).  Part of
displaying a view is displaying all its subviews.  This problem could
be solved easily if Ada had procedure valued variables, but it is my
understanding that it does not.  Please correct me if I am wrong, I
am not an Ada expert.

Ralph Johnson
johnson@p.cs.uiuc.edu      uiucdcs!johnson

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