Re: Interesting take on Paradigms (OO vs Procedural)

On Mar 29, 1:51 pm, "Rick Smith" <ricksm...@[EMAIL PROTECTED]
> wrote:
> "Richard" <rip...@[EMAIL PROTECTED]
> wrote in message
>
>
news:c3525524-b3c3-451e-b747-69eea559fc18@[EMAIL PROTECTED]
>
>
>
> > On Mar 29, 6:08 am, "Rick Smith" <ricksm...@[EMAIL PROTECTED]
> 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. 'cl*****',
> > '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 Cl***** 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.