Re: What was first: the chicken or the egg?

  Hello,

  I noticed that this one only got a one-liner from Ron, but I felt to
explain it a bit more.

  First, the better paper to refer to is:

http://users.ipa.net/~dwighth/squeak/oopsla_squeak.html

> In Squeak, what was first: VM or image?

  If we are specifically talking about Squeak, I'd say the image was
the first, but could have been in the other way.  The image was
created from the Apple Smalltalk image, and the part of the Squeak VM
was also written in the same Apple Smalltalk.

> It is said the Squeak VM is created by itself, but how to run the first image file?
> And how to creat the first image file?

  It was actually hosted in an existing (another) Smalltalk
environment.

> I wondered whether the VM C source code should be first created?

  The first VM didn't depend on any C code, but other
Smalltalk.

  And, I think a philosopher recently declared that the egg was first
before chicken.  Following his theory, a non-chicken creature bore an
egg, but it was a chicken-kind egg.

-- Yoshiki
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Hi Yoshiki,

on Wed, 28 Jun 2006 21:09:57 +0200, you wrote:
...
>   And, I think a philosopher recently declared that the egg was first
> before chicken.  Following his theory, a non-chicken creature bore an
> egg, but it was a chicken-kind egg.

Ah, philosophical software, my pet subject ;-)

Attached is the NonChickenCreature class which implements the declaration  
of that philosopher in Squeak.

Enjoy :)

/Klaus
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Thansk you, Yoshiki

Your answer is the just one that solves the puzzle in my mind.
So, I am sure you can solve another puzzle in my mind about metaclass.

All things in Smalltalk are Objects include Classes,
all Classes are instances of MetaClass.
I consider this structure bring on an  advantage that we get a clean idea,
and we can make a simple VM which needn't distinguish:
1. common objects and Classes;
2. Classes and MetaClasses.
But, why metaclass structure  like this:
http://netjam.org/smalltalk/objectMetaphysics/

- Simbba

 



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> In Squeak, what was first: VM or image?
> It is said the Squeak VM is created by itself, but how to run the first image file?
> And how to creat the first image file?

Something always needs to start things off. Although we're still trying to figure out the exact spark that created life itself, I always liked the idea of a homunculus as the "unknowable prime actor".

From Wikipedia: <http://en.wikipedia.org/wiki/Homunculus>

The concept of a homunculus (Latin for "little man", sometimes spelled "homonculus," plural "homunculi") is often used to illustrate the functioning of a system. In the scientific sense of an unknowable prime actor, it can be viewed as an entity or agent.
...
The term homunculus was later used in the discussion of conception and birth. In 1694, Nicolas Hartsoeker discovered "animalcules" in the sperm of humans and other animals. Some claimed that the sperm was in fact a "little man" (homunculus) that was placed inside a woman for growth into a child; these later became known as the spermists. This is not as silly as it sounds today, and neatly explained many of the mysteries of conception (for instance, why it takes two). However it was later pointed out that if the sperm was a homunculus, identical in all but size to an adult, then the homunculus must have sperm of its own. This led to a reductio ad absurdum, with a chain of homunculi "all the way down".

Today the term is used in a number of ways to describe systems that are thought of as being run by a "little man" inside. For instance, the homunculus continues to be considered as one of the major theories on the origin of consciousness, that there is a part (or process) in the brain whose purpose is to be "you". The homunculus is often invoked in cybernetics as well, for similar reasons.

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  Hello,

> All things in Smalltalk are Objects include Classes,
> all Classes are instances of MetaClass.
> I consider this structure bring on an  advantage that we get a clean idea,
> and we can make a simple VM which needn't distinguish:
> 1. common objects and Classes;
> 2. Classes and MetaClasses.
> But, why metaclass structure  like this:
> http://netjam.org/smalltalk/objectMetaphysics/

  "why" may not be the right question to ask.

  Many agree that the metaclass structure is overly complicated than
necessary.  The idea was to be able to define methods at individual
classes, and the reasoning from it reaches the current status.

  Smalltalk-76 didn't have metaclasses:

http://www.ifi.unizh.ch/richter/Classes/oose2/05_Metaclasses/02_smalltalk/02_metaclasses_smalltalk.html

surely you can't define methods at an individual class, but if you
define a factory type object that serves as a creator of other
instances (and bind it to a global variable), it can have similar
effects.

-- Yoshiki
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