Can a low-level programmer learn OOP?

Wayne Brehaut wbrehaut at mcsnet.ca
Mon Jul 16 19:16:32 CEST 2007


On Mon, 16 Jul 2007 10:10:05 +0200, Bruno Desthuilliers
<bruno.42.desthuilliers at wtf.websiteburo.oops.com> wrote:

>Wayne Brehaut a écrit :
>(snip)
> > after Bruno made the
>> claim: "OO is about machines - at least as conceveid by Alan Key, who
>> invented the term and most of the concept."
>
>Please reread more carefully the above. I do give credit to Smalltalk's 
>author for the *term* "OOP", and *most* (not *all*) of the concepts (I 
>strongly disagree with your opinion that message-passing is not a core 
>concept of OO).

One problem is that it's often not clear what lists of properties are
his definition of OOP vs. what are the intended properties of
Smalltalk--his intended impelmentation of OOP. Many of the lists begin
with the basic requirements that "everything is an object" and
"objects communicate by message passing", but the most common
"generally agreed upon" definition abstracts just four requirements
from these (changing)  lists--attempting to  separate implementation
details from what is essential to the underlying framework. As I note
below, these were:

1.  modularity (class-based? object-based?)
2.  inheritance (sub-classing)
3.  encapsulation (information hiding)
4.  polymorphism ((sub-) class-specific response to a message, or
processing of a method)

Other details in Kay's lists are considered  implementation details,
and important advances or alternatives to pevious methods, but not
required for a language to _be_ OO. It is reputed, though, that in
2003 Kay said
(http://c2.com/cgi/wiki?AlanKaysDefinitionOfObjectOriented)  "OOP to
me means only messaging, local retention and protection and hiding of
state-process, and extreme LateBinding of all things."

So I understand your accepting one of Kay's lists as being a
definition of OOP instead of "just" a description of Smalltalk, or of
accepting this fairly recent "definition" as being the true one (as
opposed to the previous lists of usually 6 properties). "It's hard to
hit a moving target!"

>FWIW, I first mentionned Simula too (about the state-machine and 
>simulation aspect), then sniped this mention because I thought it was 
>getting a bit too much OT - we're not on comp.object here.

Understood--sort of--but there is sufficient accurate information
about Simula available on the web now that it's no longer necessary to
use quotes from Kay about OOP and Smalltalk just  because they're more
accessible, as used to be the case. What would be so OT about
referring to Simulain one sentence instead of or in addition to
Smalltalk?

But I digress--my only real objection to your post was your opinion
and claim that Kay "invented the term and most of the concept": I've
never seen anyone claim that anyone else invented the term, but for
the claim that he invented "most of the concept" we need only refer to
Nygaard's claim in "How Object-Oriented Programming Started" at
http://heim.ifi.uio.no/~kristen/FORSKNINGSDOK_MAPPE/F_OO_start.html
that "Simula 67 introduced most of the key concepts of object-oriented
programming: both objects and classes, subclasses (usually referred to
as inheritance) and virtual procedures, combined with safe referencing
and mechanisms for bringing into a program collections of program
structures described under a common class heading (prefixed blocks)."

Combine this with the fact--as stated above by Bonnie MacBird (Alan
Kay's significant other)--that "Alan Kay has always publicly credited
Simula as the direct inspiration for Smalltalk, and... this
implication of taking credit for the first OOP language is not true,
it is a credit assigned to him by others, and one which he usually
rights when confronted with it." If he acknowledges this perhaps
others should too?

As has been noted before, it's often the fact that a cause becomes a
religion: true believers tend to take it over from the originator, and
this religiosity tends to blind them from the facts. Opinions and
rumours become facts, stories are invented, definitions are changed or
twisted, and another religion is born! Even those who don't belong to
the religion cpme to believe the oft-repreated stories, and then help
spread and perpetuate them. (Continuing in my original humorous vein I
was tempted to use terms like "religious zealots", "false gospel",
"propaganda",  etc., but thought better of it in case I was again
misunderstood.)

Again, I disagree only with this one claim. You make significant
contributions to the group and to ellucidating Python and OOP to the
great unwashed: in contrast, all I've done so far is complain about
those who don't accept the correct (i.e., my) definition or use of
terms.

wwwayne



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