Self-interest March 2001

self-interest@lists.selflanguage.org

10 participants
9 discussions

simple object model (was: [self-interest] selfing Self)
by Jecel Assumpcao Jr 03 Jun '01

03 Jun '01

I am sending a copy of this to the self-interest list. I hope you don't mind. On Friday 30 March 2001 04:39, Uladzimir Liashkevich wrote: > Let me join the discussion. This is a very interesting topic to me. > When I first read about Smalltalk I thought that it is the greatest > language ever. Then I discovered some difficulties with the language, > for example absense of multiple inharitance causes strange > inharitance trees like Object -> ReadStream -> ReadWriteStream. My favorite example is String, which can't decide if it should be a Magnitude or a Collection... > When I read about Self, I felt the same as in the case of Smalltalk. > Later I discovered the absense of some needful possibilities. One of > them is constructing objects on the fly. One cannot write something > like this: (| x:Y: = (| :aX. :aY | ^(| x <- aX. y <- aY |) ) |). While this doesn't work because slot initializers ("aX" and "aY" in this case) are always evaluated in the context of the lobby object, you can get the same results with: (| x:Y: = (| :aX. :aY. new | new: (| x. y. parent* = traits clonable |) copy. new x: aX. new y: aY. new) |) The reason I used 'copy' above is that I am supposing that you don't want successive calls to this method to always return the exact same object, but just the same kind of object. If that is the case but you don't want the new object to be clonable, we could use the '_Clone' primitive instead of 'copy' and eliminate 'parent*'. If you wanted 'x' and 'y' to be constant slots in the new object (you didn't show that in your example) then things do get much more complicated. It is still possible to do this using mirrors, however. But I was indeed trying to make this kind of thing simpler. > So > now I'm in process of thinking out a more flexible but yet powerful > language. By now I have implemented two experimental versions of > Self. But I need something different. Me too, but more in the spirit of Self than the Self-inspired languages of the early 1990s. > > Like a simple object model: objects are just flat association lists > > (I'll use Lisp notation below) - > > > > (x 3 y 4) > > flat list has an array structure rather than linked list? By "flat" I meant compared to this form of association list: ((x 3) (y 4)) But it is a *very* interesting question if these should be arrays or linked lists - Lists: + can be shared as the continuation (CDR) of several other lists + can be scanned using a single pointer - since you can point into the "middle" of a list there are many aliasing problems - can't be indexed into + can be as space efficient as arrays with special encoding + easy to split and put together Arrays: - need three items for scanning: base, index and size + no need to waste more than one virtual address per array + access to any element is equally fast It is easy to convert one into the other when you need to do some kind of processing for which the normal format is not very good. > Do you want to use the same semantics for a objects, arrays and > hashes? Like, (1 2 3) - array, (x 3 y 4) - object or hash? > Please describe that semantics a bit more. Every object is a list, but there are lists which are not formatted objects (the code examples below, for instance). So I must treat (1 2 3) as an object which does not explicitly list the messages it understands. In fact, the object "1" has this problem as well, but at least the number objects have special tags so they don't look like they might be a regular object. I am still figuring this out. > > append '(z 9) '(x 3 y 4) > > Is this a message-sending construction? What is the receiver? No, this was a pseudo Lisp functional notation. This would be more proper '(z 9) append: '(x 3 y 4) though the problem above shows itself here: how does the '(z 9) object understand the 'append:' message? We would have to force it to be treated as a plain list, which is getting into the reflective level and similar to requesting a mirror for an object in Self. This needs some careful design. > How to distinguish objects and methods? I am thinking of making methods internally be objects that have a special <code> "slot" ... factorial: (n 0 <code> (n < 1 ifTrue:False: 1 '(n * factorial: n-1) ) ) .... I have other ideas for blocks than quoted lists, but this will do for now. Hmmm... if instead of "<code>" I used "|" then this would look more like Smalltalk... Note that though the argument "n" has a default value of 0, it will be replaced once this code object is cloned to create a context object. > Did you get rid off keyworded selectors like a:B:C:? I used one in the above example, but at the low level the keywords aren't spread among the arguments. In a higher level graphical editor I would expect you to be able to write something like n < 1 ifTrue: 1 False: [n * factorial: n - 1] My idea is that the arguments would be underlined, but that is hard to show using ASCII in this email. > > [these nested lists can act as both "maps" and parents] > > Really good fresh idea. > It seems that all slots are assignable, doesn't it? That is something to be fixed. The implemenation must be able to tell what is changable and what is (normally, at least) constant. In the NeoLogo implemenation where these ideas came from you could write make "x 10 and simply change the value of the x "slot". It would be better to do the same thing by sending a message instead x: 10 and you could have the Self rule that unless there is a "x:" method then "x" is a constant slot. I don't know what the best way to handle assignments is. I have always felt that assignments and argument replacement should be somehow related. Kyle doesn't like the fact that assignment slots must be in the same objects as their data slots in Self (they can't be moved into the parent objects, for example). > The first challenge is to invent such system, then it can be > optimized. Remember that many people doubted that Self can be > implemented efficiently... Right, we can always hope that history will repeat itself. On the other hand, there are many examples of interesting ideas that nobody ever figured out how to do reasonably well. Dynamic parent slots in Self are an example (actually, I did figure out a way to do it but haven't tried it yet). -- Jecel

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selfing Self
by Jecel Assumpcao Jr 29 Mar '01

29 Mar '01

Here is a message I sent to the Tunes OS list: In 1986 Smalltalk was 14 years old and had been "frozen" for 5 years. Some people at Xerox Parc decided to ask "could it be better?" and one of the results was Self. Today, Self is 14 years old and has been "frozen" for the last 5 years. You can guess what I am going to ask :-) Some background - I have been having some interesting discussions about programming languages with Kyle Hayes (he was one of the initial contributors to Tunes) for many years. He designed a RPN prototype based language that was more Self-like than Kevo was, and has tinkered with Tim Budd's languages Leda (a Pascal-like language that lets you mix proceedural, OO, functional and logical programming) and Little Smalltalk (LST). I suggested that a "Little Self" would be simpler than LST, but as he looked into the issue he felt that there were many complications in the implementation. I had designed an OO Logo in 1983 and then a much better one in 1994 called NeoLogo that was more Self-like. So I started to explain some NeoLogo ideas that might help in the creation of a Little Self. Like a simple object model: objects are just flat association lists (I'll use Lisp notation below) - (x 3 y 4) is an object that associated the value 3 with the name "x" and the value 4 with the name "y". You can extend an object by adding stuff to the front of the list - append '(z 9) '(x 3 y 4) Code is just a list of "tokens" - (rocket speed: rocket speed + g) with the simple syntax <receiver> <selector> <arg1> <arg2>... where <receiver> is implied for the first selector in the list and in <arg1>. Kyle, of course, thinks the Forth RPN order (also used in Self bytecodes) would be better. I extended the object format so that if you find a list when expecting a selector then you search that list recursively - ((x : y :) 3 4) where ":" indicates an indirection - the actual value is in the top list. These nested lists can act as both "maps" and parents (think of what happens when a shallow copy is made of this object). There is more, and quite a lot that is still missing. I have these goals: - to have a system that I can explain to a 12 year old programmer - to have a system that allows a high performance implementation (on PCs, but specially on my own machines) Though this stuff is not optimized for Self (no named parents, for example) it might still be a nice base on which to build Self/R. Other systems could also make use of it. So my question is: would anybody be interested in this kind of thing? -- Jecel

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Re: dSelf - A distributed Self for JVM Platforms
by John Hinsley 18 Mar '01

18 Mar '01

Robert Tolksdorf <tolk(a)cs.tu-berlin.de> wrote: > > What jar means? Is it ps, pdf, doc. What is it? > > that is a java archive. you can run dSelf by > > java -jar dSelf_v1_0_1.jar Yes, but I _think_ you can only do this with the latest version (1.3) of the jdk. No problem, you can download it from www.java.sun.com and there's a Solaris version (as you'd expect). Incidentally, it was only with this release of the jdk that I began to see java as worthwhile! (But then, I'm a cynic.) -- ****************************************************************************** Marx: "Why do Anarchists only drink herbal tea?" Proudhon: "Because all proper tea is theft." ******************************************************************************

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Re: Fwd: Re: [self-interest] Self versus classes
by Albertina Lourenci 17 Mar '01

17 Mar '01

Jecel Assumpcao Jr wrote: > Eis o email que você não recebeu - > > ---------- Forwarded Message ---------- > Subject: Re: [self-interest] Self versus classes > Date: Wed, 14 Mar 2001 20:37:39 -0500 > From: Jecel Assumpcao Jr <jecel(a)merlintec.com> > To: self-interest(a)yahoogroups.com > > On Tuesday 13 March 2001 13:23, Albertina Lourenci wrote: > > I am preparing to submit a paper to OOPSLA'01 about an > > hermeneutic understanding of Object oriented programming. > > Last OOPLA, Rayside and Campbell proposed An Aristotelian > > understanding of object-oriented programming. > > It is based on Aristotelian logic. > > I think that the Plato versus Aristoteles debate in programming dates > at least from the mid 1980s. > > http://citeseer.nj.nec.com/lieberman86using.html > http://citeseer.nj.nec.com/48544.html > Thanks for this nice site. However you are mistaken. Hermeneutics has nothing to see with Platonic thinking. To the contrary, hermeneutics is the way of being of art. Platonic thinking would rather be being taught by the Hand of God how to paint a picture or it is rather connected to religious thinking. The eternal revelations that God reveals to men. And indeed to pursue my last postdoctorate scientific report I had simply to show that Platonic reasoning does not fit human reality anymore. The new modern God manifestant Baha'u'llah has the truth for the modern times. Among them the truth that the woman is equal to the man. This was stated in 1853 in Persia and give rise to the new modern religion baha'í faith !!!! There were twenty thousand martyrs! Moslem martyrs stating that the woman is equal to the man!!! Among other truths! The overwhelming majority of Western men around me are not more than blatant chauvinist pigs!!! This challenges human comprehension!!! And of course women are evolving however they do not care very much if they are still rather dependent on men for everything. To dismantle the Platonic thinking followed by philosophers such as Heidegger, and poets such as Rilke and abstract artists such as Mondrian and Kandinsky was not that easy. They all wanted to create a new scale of value for the new world at the beginning of the twentieth century. And of course their "new scale of values" based on Platonic thinking necessarily implied the inferiority of women!!!!!!!!!!! Hence hermeneutics is thoroughly worried in revealing the thingness of things and hence opening the gate to a new way of thinking based on qualities associated with opening, ability of new discoveries, courage to jump into the unknown and becoming trailblazers necessarily leading to a creative life. And the hermeneutic creative implies above all to mimic the autopoietic nature of life. It essentialy has the nature of the dialogue, the play, the form of the question and so on. > > > It seems to me that the computer scientists have difficulty > > in truly grasping the thingness of the things that can be > > very well expressed in OO paradigm. > > Most computer scientists have a pure mathematical background or > inclination. Alan Kay divided his time between mathematics and > molecular biology. That problably helped.. Sure. Being concerned with Biology since I was twelve years old especially molecular biology and genetics made it easy for me to develop my ecodesign model and identify the OO paradigm is fundamental to implement it. > > > > Hence they insist on focussing the class concept as central in > > OO programming. > > It was a key concept in Simula and Smalltalk. Most languages that > followed them just took classes for granted, specially since they fit > in so well with abstract data types (ADT) that everyone was worried > about in the late 1970s. > > > I will take for granted this to ease the discussion. Of course > > my opinion is that the object is the central concept. > > It is called "object oriented programming", after all, and not class > oriented programming. Classic programming, perhaps? > Yes because computer scientists are rather interested in implementing scientific projects hence demanding an Aristotelian understanding of the phenomena around us. Mostly top-down approach. However OO programming eases bottom-up approach. Especially prototype based languages.What I think is terrific here and confirms the truth of my search towards hermeneutics is the redirection of Alexander's trends of research tuning with the hermeneutic thinking. In his lecture delivered at OOPSLA'96, invited by Jim Coplien since he was the inspirer of the Design Patterns of the GOF and published at IEEE Software September/October 1999 he emphasizes the need to identify living structure with a reasonable level of objectivity, and once having identified the primitive elements of all wholeness, namely a recursive structure based on repeated appearances of a single type of entity. He calls these entities centers. He pursues all wholeness is built from centers, and centers are recursively defined in terms of other centers. Centers have life or not in different degree, according to the degree that the centers are built from other centers. He pursues stretching a bit, he thinks there may even be a little bit of a connection between the geometric centers which appear as the building blocks of all life in buildings, and the software entiities that you call objects. Centers are field-like structures that appear in some region of space. They don't have sharp boundaries, buth they are the focal organizing entities that one perceives at the core of all pattern, all structure and all wholeness. Everything is made of these kinds of centers. For me it is evidently a nice description of how is programming in Self (I would like to hear here the opinion from Randy and Dave of course!!!).(page 77-78) He insists this insight goes far beyond the power of the pattern language. Although the patterns define relations which might be regarded as specific instances of the recursive interaction of centers, the overall view of centers gives a more comprehensive and more powerful results. Hence for me it is the same as telling that the design patterns are better implemented through delegation that class inheritance as the prototype based community agrees. > > > So I would like Mario to join the discussion. I have reread his > > nice paper about self includes:Smalltalk. > > He implemented in a direct and straightforward way Smalltalk > > in Self in three weeks. > > The point here is that to exploit Self's possibility of let's > > say translating a language into it, in my opinion is not the > > same as stating that we can simulate in Self efficiently and > > safely like in C++, Simula or Eiffel the class concept. > > Please note the paper's title: "Self includes: Smalltalk". The whole > point was to prove that Self is a valid dialect of Smalltalk. Self was > designed by starting out with Smalltalk and eliminating many > distinctions (inheritance versus instanciation, instance variables > versus global variables, object cloning versus method activations and > so on). Some people thought that with all these simplifications Self > might have become less than Smalltalk. Mario showed that just adding a > few support objects and a parser (since there are slight syntax > differences) full compatibility with Smalltalk-80 was obtained. > > A very different effort was Pep, which translated Java bytecodes into > Self bytecodes. This just made use of the virtual machine (much as > several languages have made use of Java's virtual machine) and not > really the Self language itself. Nobody would argue that Self is a kind > of Java :-) > > Of course, you can implement nearly any language in nearly any other > language. That just proves that computers, and languages, are universal > machines. But writing a Lisp interpreter or compiler in C says very > little about the relationships between those two languages. > > But Mario didn't implement a Smalltalk interpreter or compiler in Self. > He didn't even just use the Self virtual machine to run translated > Smalltalk code (though it did that). He made use of Self's boolean and > integer objects among others. The new Smalltalk objects *looked* like > Self objects and could be used as such. > > This effort did prove that the full semantics of classes, as > implemented in Smalltalk, are available in Self. C++ or Eiffel classes > are another story. > After citing Alexander as above, I believe the doubt in understanding the gist of Self is over. And if Mario grasps the power of Alexander's saying he would not be concerned anymore with this kind of concern. What matters, SELF IS HERMENEUTIC AND Smalltalk is not. A dialect that has a different nature from Smalltalk!!! This is divine! > > > Suppose the user wants to implement in Self the classification > > of the families, genera and species. Is Self fit to do this? > > Sure: make genera objects the parents of species objects, and the > family objects the parents of genera objects. > > flipper = ( | species* = tursiops. > age <- 3. > > | ) > > tursiops = ( | genera* = truncatus. > popularName = 'bottle-nosed dolphin'. > color = paint named: 'gray'. > > | ) > > truncatus = ( | family* = delphinidae. > > | ) > > delphinidea = ( | suborder* = odontoceti. > > | ) > > odontoceti = ( | order* = cetacea. > spiracles = 1. > hasTeeth = true. > > | ) > > cetacea = ( | infraclass* = euthenia. > forwardLimbs = paddles. > rearLimbs = false. > > | ) > > euthenia = ( | subclass* = thenia. > placental = true. > > | ) > > thenia = ( | class* = mammalia. > eggLaying = false. > > | ) > > I don't think this could be done any better in another language, and > would actually be worse in many of them. > I do thank you for the sweet example with the dolphin. But by now it is clear to me that Self has more strongly the same nature of my ecodesign model I mean the classes construction in Self has the flavour of reasoning as an autopoietic entity. I mean it is very easy to handle though different, arbitrary objects united in a class concept. For example a neighborhood consists of many different buildings. LIkewise due to the prototyping allowing differential programming, this magic effect can result in Self. Hope you grasp what I mean. Class programming only allows for similar objects hence calling the urgent need for design patterns to reach more expressiveness. > > > If so why then computer scientists even enjoying and loving Self > > have difficulties to understand it and program in it? > > Not many people have ever seen a running Self system. I don't think > that those who have had problems understanding it or tried to program > in Self and failed. If that is the case for anyone on this list, please > speak up so we can find out what is wrong. > Well, here at the LSI where I work, there are people interested in Self and build nice things for electrical engineering purposes. When I asked them simply about how to use the collections, they simply stated I do not need this!!!!! However as you know collection are fundamental to implement my ecodesign model. Moreover all the graphical reasoning implied. Indeed I enjoy programming in Self however it sounds to me like biochemistry. And I hated this very much. I almost gave up scientific high school to classic high school because I could not stand this fragmentary viewpoint in chemistry and organic chemistry. > > I have seen many people who have read a few of the papers and didn't > get what it is all about, but that is an entirely different matter. > The papers are gorgeous, however the view conveyed is always fragmentary. So I do not really understand how Self programming environment really is. I do not have a whole view of it. Please Jecel I am not receiving my own messages through Self list. How can we mend this? Thanks for your kind attention once more. Have a fun-filled weekend, Albertina > > -- Jecel > > Your use of Yahoo! Groups is subject to > http://docs.yahoo.com/info/terms/ > > ------------------------------------------------------- -- .----------------------------------------------------------. | Albertina Lourenci | | PhD in Architecture and Urbanism | | post-doctorate researcher | | Laboratory of Integrated Systems University of Sao Paulo | | Avenida Professor Luciano Gualberto, 158 Travessa 3 | | CEP: 05508-900 | | Sao Paulo Sao Paulo State Brazil | | Voice: +55 011 818 5254 | | Fax: +55 11 211 4574 | .----------------------------------------------------------.

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(no subject)
by OakFlats＠aol.com 16 Mar '01

16 Mar '01

unsubscribe

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dSelf - A distributed Self for JVM Platforms
by Robert Tolksdorf 16 Mar '01

16 Mar '01

Hi, this is to announce dSelf, whose homepage is at http://www.cs.tu-berlin.de/~tolk/dself/ dSelf is an extension to the delegation- and prototype-based object-oriented language SELF. It adds distributed objects and transparent remote reference resolution to the languages. As a consequence, dSelf facilitates distributed inheritance and instantiation mechanisms. This is currently a first version and we are glad to receive whatever comments. Ciao Robert and Kai -- Dr.-Ing. Robert Tolksdorf | Technical University Berlin _______ _ mailto:tolk@cs.tu-berlin.de | FB 13 - FLP/KIT - FR 6-10 (_ _ | | http://www.cs.tu-berlin.de/~tolk | Franklinstr. 28/29 | | | | | tel: +49-30-314-25184 (FR6071) | D-10587 Berlin / Germany `-' `---'

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[Fwd: Self versus classes]
by Albertina Lourenci 14 Mar '01

14 Mar '01

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computer for Self
by Jecel Assumpcao Jr 07 Mar '01

07 Mar '01

This looks like a cheap way to run Self: http://www.sun.com/desktop/sunblade100/ -- Jecel

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Re: [self-interest] Digest Number 116
by Mario Wolczko 02 Mar '01

02 Mar '01

Stefan Matthias Aust writes: > Squeak notices if there's an error when it tries to display a morph. In > that case, a special flag is set so that this display method isn't called > again until somebody fixes the problem and manually resets that flag. A > flagged morph is displayed as a gray box with two crossing red lines. This is exactly what Self does (except for the gray box and red lines) - Randy and I put this code into 4.0, in '95 (before Squeak). See our CACM paper (vol 4, #4). When it was built, the UI was pretty robust -- we had numerous sessions with multiple users in the world at the same time, doing development. Randy and I demo'd this at ECOOP 95. If it's fragile now, it's because bitrot has set in somewhere, not because there is an inherent problem. Jecel writes: > For 32 bits, 2G is a positive number for C unsigned variables but a > negative number for signed ones. I took a quick look at space.c in the > VM sources but didn't get far enough to see if this could be your > problem. The VM has no idea how much real memory is installed. That certainly isn't the problem. Mario

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Self-interest March 2001