Re: Interesting take on Paradigms (OO vs Procedural)

On Mar 29, 1:51 pm, "Rick Smith" <ricksm...@xxxxxxx> wrote:
"Richard" <rip...@xxxxxxxxxxxx> wrote in message

news:c3525524-b3c3-451e-b747-69eea559fc18@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx



On Mar 29, 6:08 am, "Rick Smith" <ricksm...@xxxxxxx> wrote:
<http://www.cs.berkeley.edu/~jrs/4/lec/14>
-----
Why did the originators of object orientation rename "structures" to
"objects"
and "procedures" to "methods"?

Because they weren't 'programmers', they were simulation modellers.
Simula was/is a language for writing computer based simulations. For
example a petrol (gas) station will have a number of pumps, staff and
cars will arrive at various rates wanting various products and
services. Queuing theory will show some features, such as average
wait times, but simulation will give more information.

What is required in a simulation language is the ability to specify
different behaviours in the various objects being simulated. Some
drivers will bypass a gas station if the queue looks too long, or will
wait a variable time in the queue before giving up. 'classes',
'objects' and 'methods' is the language (jargon) of this activity, and
has been since before there were computers.

The book "Simulation Using GPSS", Thomas J. Schriber,
1974, covers the use of General Purpose Simulation System
to accomplish discrete event simulation. I find no mention of
"class", "object", or "method" in this book; thus, apparently,
these terms are not in the jargon of GPSS users. The author
uses procedural languages as a model for explaining the use
of GPSS.

Turning to my* copy of "Programming Languages. NATO Advanced Study
Institute, edited by F Genuys 1968" it has an article "Discrete Event
Simulation Languages" by Ole-Johan Dahl. This apparently was given as
a series of lectures around 1966. It discusses simulation in general
and how some computer simulation languages map onto the process.

In part 3, Basic Concepts:

"""... We think about a system as in terms of the objects that it
contains. The statis of the system is defined by the status of each
object and by the relations that hold between objects.

3.1.1 Classes of Objects

.... This conflict is resolved by the technique of classifying objects.
.... status descriptors called attributes. An attribute is a
variable, ...

The class concept vastly simplifies the description of a system. A
qualitative declaration of a class of objects serves as an en bloc
description of every member of that class.
"""

After a few pages of these concepts there is a section that indicates
the terminology of several programs and how the concepts relate to the
terminology used by the programs. The programs are GPSS, SOL,
SIMSCRIPT, CSL and SIMULA. For example in GPSS an 'attribute' is
called a 'parameter', an 'object' is called a 'transaction', GPSS
doesn't implement anything related to 'class'.

Later it discusses 'reference counting' and 'garbage collecting'

It seems that the point is clearly made that discrete simulation as a
discipline used the terms we see in modern OO languages whereas the
computer simulation languages of the time (mid 60s), including SIMULA
of 1966 (and GPSS), were implemented by computer programmers who used
the terms that they were used to.


* I say 'my copy' in spite of the "ICL Head Office Library" stamp on
the front page and 'date due' slip affixed to the last. If this wasn't
blank it would have some date in 1970 stamped on it.

.

Relevant Pages

  • Re: Interesting take on Paradigms (OO vs Procedural)
    ... Because they weren't 'programmers', they were simulation modellers. ... Functional languages: Lisp, Scheme, Haskell ... Cobol from accounting, Fortran from engineering, APL from mathematics. ... Thus class data is a struct, ...
    (comp.lang.cobol)
  • Re: Interesting take on Paradigms (OO vs Procedural)
    ... Because they weren't 'programmers', they were simulation modellers. ... Functional languages: Lisp, Scheme, Haskell ... It happens that OO features were grafted on to existing computer ... Thus class data is a struct, ...
    (comp.lang.cobol)
  • Re: Not enough parallelism in programming
    ... >> Trying to model this in occam and I suspect in most any SW par language ... SW languages don't want or need the ... Funnily enough nor do some hardware projects if some simplifying ... simulation trades speed and simplicity for the event driven simulator ...
    (comp.arch)
  • Free GPSS Simulation Books
    ... My GPSS simulation days are past- wrote a masters thesis some 40 yrs ... Thomas J. Schriber ...
    (comp.simulation)
  • Re: Interesting take on Paradigms (OO vs Procedural)
    ... covers the use of General Purpose Simulation System ... these terms are not in the jargon of GPSS users. ... edited by F Genuys 1968" it has an article "Discrete Event ... Simulation Languages" by Ole-Johan Dahl. ...
    (comp.lang.cobol)