Self-interest January 2001

self-interest@lists.selflanguage.org

18 participants
22 discussions

egroups has problems with thread structure ?
by Thilo Schwidurski 23 Feb '01

23 Feb '01

Hello, is there a way to post a reply *via email* *without* loosing the thread structure ? Did you make the same experience ? Anyway : I posted 954 as a reply to 946, 955 as a reply to 947 and 956 as a reply to 949. Regards, Thilo.

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subjective programming
by Jecel Assumpcao Jr 05 Feb '01

05 Feb '01

I had been thinking about subjective programming lately, and happened to find an online version of the Us paper: A Simple and Unifying Approach to Subjective Objects (1996) Randall B. Smith, David Ungar http://citeseer.nj.nec.com/smith96simple.html Us is an extension of Self for subjective programming, and the only thing I had been able to find about it previously was this short position paper: The Subjective Prototype Randy Smith http://www-staff.mcs.uts.edu.au/~cotar/proto/randy.txt I first started considering objects with different viewpoints in terms of the user interface. On the previous version of this mailing list (in October 1990), I proposed that we could view objects through a set of "lenses". This Xerox project actually implemented this: http://www.parc.xerox.com/istl/projects/MagicLenses/ What an object looks like depends on what lens you view it through. Since another teacher at PUC-SP called my attention to the problem of "roles" in object oriented programming, I tried to include these features when I designed a Logo compatible, Self derived language in 1994. NeoLogo only allowed an object to extend one other object; a kind of "single inheritance". But this was very dynamic, so I came up with the idea of allowing multiple children to model the different roles for an object. There was a very complicated operation called AS. So the expression X AS Y would: - return Y if Y was a child of X - return Y if X was a child of Y (true! this rule was to allow AS to work as a kind of resend) - return Z if Z was a clone of Y and Y was a child of X - return Z if Z was a clone of Y, W was a clone of X and Z was a child of W - signal an error, otherwise There was also an ASNEW that was just like this, but instead of returning an error in the last case it created a new clone of Y that would satisfy one of the previous two rules. This seemed to solve the magic lenses and roles problems, so I was surprised at Ecoop95 by a paper claiming that delegation (what I was using could be considered that) wasn't the right tool for this job: Sharing Properties in a Uniform Object Space Heiko Kießling and Uwe Krüger http://link.springer.de/link/service/series/0558/bibs/0952/09520424.htm Their system seems similar to the Beta language in many ways, but they allow a single object to have several views. An advantage over my idea was that objects didn't change identity when you changed views. The Us language has this advantage as well. And the view is defined as a part of the sending context which is by default inherited by the receiving context. This means that many objects change when you change views (AS in NeoLogo encoded the view in the object identity and so only the receiver was affected - all other objects looked the same as before. NeoLogo also had the nasty "rubber band" semantics described in the Us paper). While the paper introduces a new syntax for changing views, we could use the existing Self parser and bytecodes by doing something like [ some expressions ] >< newView The examples of how it could replace meta-objects for reflection and how they could be used for versions and multi-user objects were particularly interesting for me. With some additional semantics (if you could have copy-on-write views) you could even use them for transactions: if you throw away a transactionLayer and let the garbage collection have it, it is an abort; but if you explicitly merge it with another view then that is a commit. Of course, multiple graphical views are interesting too and the reason I was thinking about all this. I wanted to do a graphical version of my CMOS simulator but needed a schematic view, a layout view, a component view, a simulated schematics view, a simulated layout view and so on. My design was to create a copyAs: method which would copy "split objects" as indicated by view objects (special dictionaries). I have no idea of how to implement this efficiently, but was wondering if the people in this list (specially Randy and Dave) think it is a worthwhile idea. -- Jecel

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First
by Stefan Matthias Aust 02 Feb '01

02 Feb '01

Hi! Yesterday, I played two hours at my company with a real Self system (version 4.1.2). Only my colleague was more excited than I was, even if he didn't know anything about Self and was just playing around with the UI, recoloring and resizing windows and watching me searching the system to find out how to make cursor keys workable. It was fun even if it's a five years old system. Although I've a few questions and comments. In random order... The first time, the system crashed was when it said it couldn't allocate more than 130 MB of memory. I don't know why it wanted that much memory and frankly, I don't care. However, my system has 2048 MB of memory, so my question is, why couldn't it allocate more memory. The second time, the system crashed was when I assigned a number to a label morph (probably instead of a string). I agree with my colleague, the UI seems to quite fragile. Self tried to open a new world but still, it flooded my with debuggers. I like the way Squeak deals with display errors much better. Opening a morph factory freezes the whole system for 5-20 seconds. I think, this is unacceptable for a multi user system. I've run Self on a 2 x 440MHz SPARC system. It could be the multi user display or simply the age of the system, but compared to VisualWorks on the same system, Self feels slow on the UI. It seems that the Smalltalk emulator is missing in the current distribution. The web browser throws an exception because a paint mgr doesn't understand some messages. It seems, there're some 24 bit-depth bugs. From time to time, I got strange errors like 4673826438 doesn't understand asVMByteVector (so some similar message, I don't exactly remember), perhaps because some missing 24 bit-depth support? When using the multi user mode, shouldn't every user have his own radarView morph which is inaccessable for every other user? Now, by navigating away, I was able to leave my colleague alone on the start screen which no chance to follow me. We then duplicated a viewer but now two or more viewers always cluttered the screen. The system wasn't able to get our names. Both mouse pointer were called "Andre" which is the forename of first employee in the passwd file but neither my nor my colleagues name. I love the core sampler! (This had to be said ;-) When changing methods, that's the best way to collect changes to post or publish them? There's changed modules morph, but it seems that it can only write complete modules. It also crashes if the directories it assumes don't exist. Is it correct that there's no change set concept as in Smalltalk? It seems the Self image contains all source code. Why? Wouldn't it be better to have a system similar to Smalltalk where source code and changes are stored in external files and the image would contain only pointers to that files? I really missed Squeak "revert" and "versions" menu commands. They're easy to implement once you've the concept of a changes file. When I was playing with the system trying to colorize a propertiesSheet morph, I managed to color it red but then lost track what I'd changed and couldn't find the place again. Is there a way to list and browse changed methods - and as multiple people can change methods, sorted by user? What's the best way to change the value of an assignable slot (the one marked with ":"). I tried to open some kind of inplace editor but that seems to work only for the slot name, not the slot value. So I always had to open a shell for that object and evaluate things like "width: 2". At least for simple literals, it would be nice if you could directly enter the new value. Does the text editor require a non-proportial font? Or is any font possible? How can I change that? What's about the font size? Is there a way to automatically update object outiners? When I change values, it seems that the new values are shown after a short time but I don't know whether this is a feature or simply happened by accident because the morph was redisplayed. A manual update option would be nice. It also would be nice if all "tools" would behave and look the same. I dislike the fact that most tools don't have a close button. Interestingly, in the barebone image, the debugger has one while in the demo image, it has an "abort" push button. But overall, Self is really cool. How I'd like to use it also at home on an Intel PC... bye -- My eyes adapted to the darkness... finally I can see clearly now

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Re: [self-interest] Info about Pep?
by Stefan Matthias Aust 30 Jan '01

30 Jan '01

At 11:06 23.01.01 -0800, you wrote: >Would Mario's work to emulate Smalltalk in Self be considered >similar. Is this a question? I don't think so. Converting Smalltalk to Self is pretty easy compared to converting Java, especially Java bytecode, to Self (or Smalltalk). Overall, the approach to go is pretty obvious, but quite a few details of the Java VM specification like synchronized methods or exceptions make things difficult if you want to get good performance. However, the idea is intriguing as not "Java the language" but "Java the waste amount of libraries" is what I'd like to use. For this, you'd however need to translate bytecode and probably also support JNI. bye -- Stefan Matthias Aust // Bevor wir fallen, fallen wir lieber auf

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Ported Gordon's self4st to VW5i
by Stefan Matthias Aust 28 Jan '01

28 Jan '01

Hi! I found an old, unfortunately incomplete Self in Smalltalk on Gordon Cichon web page which he wrote years ago and now published under the GPL. For curiosity, I took the freedom to port it to VW5i.3 beta, fixing two or three bugs and also added the "{}='...'" syntax variant which Gordon said was missing. Although, I haven't tested yet to file in any official Self code. Before you can do that, you'll have to implement 50+ primitives I'm afraid. However, if anybody wants to continue, drop me a note and I'll send you the code. bye -- Stefan Matthias Aust // Bevor wir fallen, fallen wir lieber auf

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Info about Pep?
by Stefan Matthias Aust 27 Jan '01

27 Jan '01

Hi! I just learned about Pep, a Java to Self translator which was created in 1997 at Sun Research. I found the paper very interesting. Does anybody know whether Pep is part of the current Self distribution or whether it is freely available? I'd to be able to study the Self code. I'd also be interested in opinions how Pep relates to Parcplace's Frost project which seems to have taken place at the same time. Frost is a Java source/bytecode to VisualWorks Smalltalk bytecode translator plus IDE for Java 1.0.2. It was open sourced a few weeks ago. bye -- Stefan Matthias Aust // Bevor wir fallen, fallen wir lieber auf

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Brain language
by Steve Dekorte 27 Jan '01

27 Jan '01

Ran across this while surfing the net and thought the group might find it interesting: http://brain.sourceforge.net/ Brain is a high-level, purely object-oriented, prototype based scripting language, mostly similar to the Self language.

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programming and knowledge representation
by Thilo Schwidurski 23 Jan '01

23 Jan '01

Dear members, the group lately adressed unification of languages (vs. "Babel effect") and metaprogramming and other philosophical concepts. So I felt that it might be a good place for a discussion of some thoughts about programming and more general about knowledge representation. Please forgive in the case that I even use whole phrases that were already written here (or elsewhere) without quoting properly - in the end nothing I have to say is possibly really new - maybe/hopefully except of the overall picture. But I can say that I definitly got inspired and encouraged by the Self-, the Merlin- (Jecels not Suns), the Tunes project and of course of all of what I read from you that are devoted to thinking about programming in this group (and a couple of others). A first helpful step to deal with the "Babel effect"-problem could be changing the view on what programming is. I see Programming (perhaps a bit more general as usual) as gaining and writing down knowledge. You could associate "gaining knowledge" with "designing/architecturing programs". I don't see so much use any more in the partitioning of knowledge in data and programs/algorithms. An example: every program code that contains constants contains "plain" data. Every database that contains a kind of rules (I am thinking of values of string-fields that contain code) contains programs. So what I am aiming at ? - Knowledge can be represented as a directed graph, which' nodes could be seen as extremly fine grained objects - possibly only "containing" one value of a POD-Type like String or Number. Maybe there has to be also a Bitarray Datatype but 'only' for efficiency in storing "multimedia data" streams. All other common named properties of objects like attributes, methods, inheritence parents (each also representable by slots) and types are realized by named edges. An edge can be named because edges can also be connected - with edges or objects. The names are just objects (a string-value-node). This special graph (I would like to call it hypergraph but the term is already defined differently - so I will just refer to it as graph) can be seen as an "amalgamated structure" of semantic networks, object networks and hypermedia in respect of what it can represent. I see it as kind of "mother of representations" or *the* model (like in model-view). One motivation for this represention structure is that I found that the relations between objects are at least as important as the objects itself. For example is deleting an object almost always really the unlinking of two objects (that a historizing mechanism can and should take care of). - The basic language concepts (message passing, delegation to prototypes and classes, ...) can be plugged in (and perhaps sometimes even out of) the environment (that means getting assigned to the "environment?-object"). I am not sure if this is partly not even already state of the art in Smalltalk/Self/other environments. - To represent code of the conventional textual programming languages each language concept can be assigned to an arbitrary syntax (of course carefully, without violating inherent constraints like "no two concepts may be assigned to the same syntax within the same environment") or even a set of alternative syntaxes. For example would I prefer to write down mathematical code expressions in the common mathematical symbol language (probably enhanced to be computer-interpretable). As far as I know there are functional languages that have this feature of syntax-adaption. I am not sure at all (because I never designed a language) if this "separating of concepts" works at all. I just have a good feeling that it should anyway ;-) - Each language concept is assigned to (and gets processed by) an interpreting machine (part of a compiler or interpreter or VM) - this machine solely works with the underlying graph (seeing it as the traditional AST-structure). - All the other common representations (e.g. textual program code, but also "more visual" representations like UML, just everything that is known as hypermedia) can be generated (temporarily) as *views* an the graph by transforming-adapters. - A persistence-mechanism (mapping between different "layers" of storage) only deals with graphs (resp. queried portions of the "whole" graph). That means that the underlying graph/OO-database (virtual memory management ? - I get confused what the different "parts" of the concepts behind these terms really are) just works with graphs. - Historizing information is embedded in the graph and the processing and usage of it is a crucial part of the KlDE (knowledge development environment) as it seems to be very important to being able to track the evolution of knowledge (especially the evolution of the linking). - Also like Historizing is Personalization (think of ownership, authorship and privacy) a basic concept that has to be serviced by the system. - After all could this system be the foundation of something like "open knowledge" (in contrast to "open software") development - aiming at breaking down the borderwalls of heterogenic knowledge representation systems (possibly just yet another holy grail dream :-/ ...). I shurely hope this ideas are not to far away from your interests and would love to discuss them with you. Regards, Thilo.

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abstract syntax grammars
by Albertina Lourenci 21 Jan '01

21 Jan '01

Dear Selfers: Let's make things simple. Having read Chapter 3 Syntax from Bertrand Meyer's Introduction to the Theory of Programming languages (he is the author of Eiffel) I would like someone to tell me if the syntax of all programming languages (even functional languages? or everything comes from functional languages?) are described by a grammar consisting of a set of productions; each production describes the form of a certain class of language elements such as instructions, expressions, routines, etc? Thilo, my darling I am very sorry but after having spent lots of time responding to your nice message the send message command had a problem and I lost the message!!! But what is fundamental is that there was a mistake in the message. The paper Annotating objects for transport to other worlds was published at OOPSLA'1995 Proceedings and could be downloaded at http://self.smli.com/ ~ungar (Dave please is it OK?). On page 84 Dave states 5. Previous Work The Beta fragment system is more versatile than the transporter because while the transporter cannot dissect slots, a Beta fragment can be any abstract syntax tree node. Moreover he puts forward (ASTs defined by the context free grammar may be described as Lisp S- expressions - What's this? and how it is related to ASTs?) that in the Interlisp environment data were represented as S-expressions and Loops objects (built out of S-expressions).Then he traces the differences and similarities between Interlisp and Self. Why did Dave talk about these things? We were talking about expressiveness. So here the use of ASTs affects the Beta fragment how? Moreover Meyer argues there are two ways to describe the details of the attribute approach: a procedural way or an OO way, where the emphasis is on the constructs. So is it at the level of the attribute grammar that an OO language is defined? In this approach constructs will be viewed as abstractly data types such as classes in class-based languages, patterns in Beta and object in Self? Madsen states that the highly interactive, integrated and incremental programming environments of many Lisp systtems such as Interlisp are in many aspects much more advanced than most environments for developmet of production software. So if Self and Interlisp environments are similar, how can I understand the Self environment better? And in this case the language is designed according to a set of production? Well I feel this is not the case because Dave says The beta system embodies a very classical view about the nature of a program: a Beta program is a collection of abstract conceptual patterns that describe concrete phenomena without themselves partaking of the concreteness of the phenomena. Hence only the metaprogramming tools in the Mjolner Beta System manipulate programs through a common representation, that is ASTs? My question is one uses ASTs to design programming languages as well the programming environment? I am very confused. Thanks for your kind attention. Albertina -- .----------------------------------------------------------. | 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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Re: [self-interest] programming and knowledge representation
by Brian Rice 18 Jan '01

18 Jan '01

>I think that Brian Rice's Arrow project/idea develops on more or less >the same view (although he likes to use bigger words). I don't know >where the Arrow site is today, or whether he's still working on it (last >I heard of him, he was working on the Slate language/object system), but >it should be somewhere in the bespin.cx server. > >-- Kaufmann > >"Every man is as God made him, yes, and often worse." - Miguel de Cervantes Definitely so, although arrow is on the "back-burner" while I make sure Slate works properly. Slate embodies some arrow concepts, but not even close to all of them. Arrow is an information system that's not really classifiable by the current state-of-the-art in information (or "knowledge") systems research. Unfortunately, my thesis papers on this subject are far out of date compared to my current state of knowledge on this (which has grown by orders of magnitude). Also, all of my research is amateur due to a lack of patronage. So for now, things are under wraps until I decide otherwise. Even so, the Tunes site has an early copy of my Arrow design philosophy draft. However, I don't believe that this discussion is really appropriate to this list. I'd rather hear less about the vague notions of "knowledge engineering" and more about language and system design issues. All knowledge is expressed in some language, whether at one level or another. A language expression might evaluate into a structure which is the information, or the expression itself might include or encapsulate the information in various ways. The intricacies of how this is done is embodied by studying what "meta" means in context, which incidentally is always relative to some core calculus, which in Self's case is not the language itself. The Self language in fact consists of several distinct phases of speaking about objects, which is part of my interest in it. Just my 2 cents' worth. ~

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Self-interest January 2001