On 19/07/12 07:09, rusi wrote:
On Jul 19, 6:34 am, Steven D'Aprano<steve
+comp.lang.pyt...@pearwood.info> wrote:
On Wed, 18 Jul 2012 15:40:00 +0100, Lipska the Kat wrote:
Object Oriented programming is all about encapsulating human concepts in
a way that makes sense to human beings. Make no mistake, it is NEVER the
case that a software system is written for any other reason than to
serve human beings. OO is more than just the mechanics of writing code,
it's a state of mind.
Um, yes?
Its not so much a question of language as in programming as language
as in layman-speak.
One characteristic with our field is that we take ordinary words and
then distort them so much the original meaning is completely lost.
Take 'computer' for example. For Turing a computer was a
mathematician doing a computation with a pen and paper. He then
showed how to de-skill the mathematician so much that a machine could
do what he was doing. In trying that he also hit upon the limits of
such 'de-skilling' -- human-computers routinely detect infinite loops,
whereas machine-computers can never do so (in full generality).
Ironically the important lesson is lost and today 'computer' is
synonymous with machine.
Here is Dijkstra on similar distortions with 'user' and
'intelligent':
http://www.cs.utexas.edu/~EWD/transcriptions/EWD06xx/EWD618.html
'Object' (and OO) are similar messes.
Well this is all very interesting.
The terminology is quite concise if you allow it to be
Take "An Object is an instance of a Class"
A Class describes a human concept (be it concrete like a 'Parrot' or
more abstract like a 'Session') an Object is an actual representation of
that concept that exists in the memory of a computer (what else should
we call it). Objects don't exist in the mind of a human, concepts do. A
class is a way of representing that concept so that other humans can
understand it. That's it, really, there is no more, anything else is
implementation.
In layman-speak and object is well, a thing.
But we are not talking in 'layman-speak' we are discussing concepts that
are familiar to us in the 'language of the domain' at least I though we
were. Academic twiddling with the distorted meaning of words spun by
vested interests is all very interesting I'm sure but doesn't really
advance the discussion does it?
- subject to space-laws like can only exist at one place at a time,
there cannot be two objects at the same place and time etc.
- subject to time-laws like coming into existence at some time and
going out at some other
- connotes inanimateness unlike other 'creatures' or 'beings'.
Well here I have to agree with you. Anyone who invents a 'Person' Class
should be dismissed forthwith. Parrots are OK though.
When this metaphor works (for example as in guis and simulation) then
we have success-stories like smalltalk and simula.
When it doesn't the success is poorer. eg a programmer writing math
software in/on a OO system may for example 'clone' a matrix. This may
be good science-fiction; its bad math.
And one of the most pervasive (and stupidist) metaphors is the parent-
child relation of classes.
Just for the record, in the normal world 'creatures/beings' reproduce
and therefore inherit.
But we are not talking about the 'real world' are we, we are talking
about representing complex interacting human concepts in a way that can
be understood by humans and translated into a form that can be executed
on a binary machine
> Objects dont.
Well they do, it's a fact, you can call a method on a sub class that
only exists in the super class. What else would you call it.
Well it's been fun but I have bills to pay so I suppose I'd better do
some work. TTFN
--
Lipska the Kat: Troll hunter, Sandbox destroyer
and Farscape dreamer of Aeryn Sun.
--
http://mail.python.org/mailman/listinfo/python-list
