Re: Object Oriented differences between Smalltalk and Ada

Re: Object Oriented differences between Smalltalk and Ada

[Mark L. Fussell]

David Brown wrote:
> Can anyone please help me, I have to write an essay on the object
> oriented differences between Ada and Smalltalk. Any info. would be
> appreciated, even if it was just one one of the languages.

That is a hard task: you will really have to immerse yourself in both
languages to understand how they think about the world.  Although this
is always true about language comparisons, Ada and Smalltalk are from to
completely different family trees.  The following diagram is from:
   http://www.cs.waikato.ac.nz/~marku/313/oo.history.html

                Simula
                  |              Pascal
              Smalltalk            |
             .   /:\          Modula-2
           .    / : \           /  |  \
         .     /  :  \        Ada  |   \
       .      /   :   \     / |    |    \
   Self   Obj-C  C++  Eiffel  | Oberon  Modula-3
    |             |     |     |            :
    |             |     |     |            :
    |            Java Sather  |          Python
  Cecil                     Ada95

Although I do not completely agree with the genealogy (some of the
references below include alternative diagrams), you can immediately see
the problem with comparing Smalltalk and Ada95: Ada95 is "newer" but it
was grown from a different root and is growing towards a different sun's
light[1,2].

You will need to decide what your goal is.  Smalltalk is inherently OO
programming.  Ada is not.  Do you want to compare Ada95's OO features to
Smalltalk's OO features?  Or do you want to compare some of the goals of
OO programming with approaches that can be used in Ada95?  The later is
a "fairer" comparison because Ada cares about building good software but
it does not have the same priorities and approaches as Smalltalk and OO
programming.

To immerse yourself in the languages you will need books and
environments.  You can find references to both in the corresponding
FAQ's.  The following are just samples:
   Smalltalk-80: The Language and its Implementation. 
      Adele Goldberg and David Robson. 
      Addison-Wesley, Reading, MA, 1983.

   Squeak
       http://www.create.ucsb.edu/squeak

   Ada as a Second Language, Second Edition
      Norman Cohen.
      McGraw-Hill, New York, NY, 1996.

   GNAT
       http://www.gnat.com/

A few random cross-language resources off my bookshelves:
   History of Programming Languages-II
      Thomas Bergin and Richard Gibson, editors.
      Addison-Wesley, Reading, MA, 1996.

   Programming Lnaguage Concepts
      Carlo Ghezzi and Mehdi Jazayeri
      Wiley, New York, NY, 1987

   Computer Languages, A Guide for the Perplexed
      Naomi Baron
      Anchor Press/Doubleday, Garden City, NY, 1986.

Good luck on your essay and let me know if you find some good online
resources. 

--Mark
mark.fussell@chimu.com

[1] Java on the other hand has clearly grown from the Smalltalk root
although also towards a different SUN.  And the unpredictable orbit of
that SUN and a bunch of parasitic 'c'ritters have turned Java into a
really gnarly branch. 
[2] Actually, no language has grown much beyond Smalltalk towards the
light Alan Kay was reading by.  [OK, OK, I am beating up the metaphor. 
I'll stop now :-].

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