Squeak-dev November 1998

squeak-dev@lists.squeakfoundation.org

128 participants
265 discussions

Re: squeak hogs memory on linux?
by lex＠cc.gatech.edu 04 Nov '98

04 Nov '98

Greg Lewin <greg(a)quokka.demon.co.uk> wrote: > > It's better on RedHat 5.1 and Squeak 2.2 (was 5.0 and 1.3), but I still > get similar trouble if I click on one of the buttons in "play with me > 4". > Sounds like a sound problem: those buttons trigger a sound. The stock Unix VM doesn't support sound at all. If you are using it, set "turn sound off" from the help menu. However, I have written some basic support for sound in Linux. It could use some work, but it does make the correct sounds come out. This is at http://www.cc.gatech.edu/~lex/squeak/sound/. However, it doesn't support "startPlayingImmediately", so you have to edit the startPlayingImmediately: in SoundPlayer and set "dontInsertSamples" to true instead of false. (This should probably be made a preference. Then again, someone should probably implement startPlayingImmediately on Linux!). This is all explained step-by-step at the above URL, if you are willing to rebuild an image. Then again this could be something else entirely. Lex

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Re: Toward the next release...
by Aibek Musaev 04 Nov '98

04 Nov '98

Dan, Could you please change: PositionableStream nextLitteEndianNumber: put: into PositionableStream nextLittleEndianNumber: put: "Little with l" Thanks, Aibek.

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Re: about oss doc from MS
by Hans Baker 04 Nov '98

04 Nov '98

Here it is. Enjoy. (:-) -----Original Message----- From: Matthew McDonald <mafm(a)cs.uwa.edu.au> To: squeak(a)cs.uiuc.edu <squeak(a)cs.uiuc.edu> Date: 1998Í11'¬5»' 3:31 Subject: Re: about oss doc from MS >Hi Hans, > > Folks: > > It is I that sent the confidential doc of oss from M$ to Eric Raymond. I > > am a fun of a little hacker group named "Aka" in China. Who need the > > original oss doc( in Word97 format )? Please email to me. > >I'd love to have the original in word-97 format! > >Could you send me a copy, thanks. >-- >Matthew McDonald <mafm(a)cs.uwa.edu.au> > > Attachment converted: Anon:oss.zip (pZIP/pZIP) (0000354A)

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about oss doc from MS
by Hans Baker 04 Nov '98

04 Nov '98

Folks: It is I that sent the confidential doc of oss from M$ to Eric Raymond. I am a fun of a little hacker group named "Aka" in China. Who need the original oss doc( in Word97 format )? Please email to me. Hans

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Units package (was Method names)
by Sam Adams 04 Nov '98

04 Nov '98

alank wrote: <<Reinier -- We've talked a lot over the years of adding "units" (centimeters, feet, grams, ounces, bits, bytes, etc.) to Smalltalk. They are very useful in science for knowing what you are talking about, and in Smalltalk would be a set of unarys (as you suggest) that help conversions to be made. (They also could be symbolically executed to just get the dimensions of the quantity .....). Any interest out there in making a great units package for Squeak? <snip> >> Yes, I'm interested. I implemented a start for such a package years ago and learned a great deal but the code was lost. If I remember correctly the main objects in the framework were Measurement, Measure, MeasurementSystem, Unit and a few others. It used coercions based on a "gold standard" for conversions and lots of unary messages for syntactic sugar (inch in inches squareInches cubicInches etc). Some experiences: Unit conversions within a MeasurementSystem are trivial: ( 1 inch + 12 feet ) asYards Unit conversions across MeasurementSystems( English vs Metric) for the same Measure (Linear, Area, Volume) were easy for addition and subtraction (3 meters - 2 feet) asAngstroms Multiplication and division were OK (LinearMeasure * LinearMeasure yields AreaMeasure) (2 feet * 10 meters) asHectares What got complicated fast (and what I never finished) was the general case which ends up with composite units like furlongs per cubic fortnight per dyne centimeter. You then needed an algebraic system with mappings for unit definitions (dyne cm = erg, etc) so these composite units could recognize whether they were compatible or not and if the units could be reduced or mapped to another unit. The really cool stuff you could do with a system like this is divide aDistance by aTime and get aVelocity and divide by aTime again and get anAcceleration, then multiply by aMass and get aForce. Each Measurement object would be the natural place to implement all of those equations we learned in Physics. I had dreams of an environment like Morphic where animated measurement objects would collide and react almost chemically, perhaps implementing an updated version of the old General Problem Solver. <sigh> One other piece of advice: check out a book on measurement theory or find a MathPsych major for tips on abstractions for this domain. Oh yes, Kent Beck and Ward Cunningham's experiences with financial modeling with deferred currency conversions would also be excellent here. They had some great models that might be useful. Regards, Sam Sam S. Adams, Distinguished Engineer, IBM Network Computing Software Division tie line 444-0736, outside 919-254-0736, email: ssadams(a)us.ibm.com <<Hebrews 11:6, Proverbs 3:5-6, Romans 1:16-17, I Corinthians 1:10>>

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Squeak security [changed from Re: A bit of header]
by Jan Bottorff 04 Nov '98

04 Nov '98

At 01:38 AM 11/3/98 -0300, sqrmax(a)cvtci.com.ar wrote: >What do you think about using one of the unused bits in the image header as >a flag to tell if the image was properly closed or not? This would allow the >VM to warn the user if he/she tries to open a not closed image. An example >of this is to open an image twice, which can result in a damaged changes file. If the goal is to prevent changes corruption, wouldn't it be better to open the changes file with exclusive sharing access? Mabey on the first time you write something to changes. I could easily imagine cases where you might want multiple instances of an image open, each in a different process, that never write to a changes file. For example, an end application image (people might actually want to deploy finished Smalltalk apps, not just live in the development environment). Or mabey some method of putting a checksum on an image. The very best case would be you put a digital signature on an image, not only would this prove the image was not corrupted, but could prove where it came from. The danger of viruses loading in an image seem quite real. Every time you fileIn a piece of random Smalltalk code, your image is in danger of getting infected. The Java folks have taken steps to prevent this, even the Microsoft folks have taken steps. Any kind of crypto support in Squeak might cause US export issues though :( Mabey instead of making armchair comments, I should look into what really might be done to improve Squeak security. Any pointers to previous Smalltalk security projects? - Jan ___________________________________________________________________ Paradigm Matrix Inc., San Ramon California "video products and development services for Win32 platforms" Internet: Jan Bottorff janb(a)pmatrix.com WWW http://www.pmatrix.com Phone: voice (925) 803-9318 fax (925) 803-9397 PGP: public key <http://www-swiss.ai.mit.edu/~bal/pks-toplev.html> fingerprint 52 CB FF 60 91 25 F9 44 6F 87 23 C9 AB 5D 05 F6 ___________________________________________________________________

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Re: Method names
by johnm＠wdi.disney.com 04 Nov '98

04 Nov '98

Stephen Pope was able to build a really nice "units" system using normal Smalltalk syntax. He did it in the context of a music system where you could say things like: sound pitch: 440 asHz or sound pitch: 69 asMidiKey The selectors "asHz" and "asMidiKey" are unary messages that return a pitch object, I believe. (Stephen: please correct me if I'm not explaining this correctly.) -- John

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Interesting :-) article and whitepaper on Open Source Software
by wirth＠almaden.ibm.com 03 Nov '98

03 Nov '98

Dan Gillmor had an interesting column in the San Jose Mercury News this morning, "Microsoft wary of open source, embedded systems", which you can find at: http://www.mercurycenter.com/columnists/gillmor/docs/dg110398.htm He discusses a purported internal MS whitepaper on Open Source Software (called "OSS" in the whitepaper :-) which was leaked by Eric Raymond as "The Halloween Document". You can find it, along with Eric's analysis and marginal comments (with ongoing updates, now at version 1.4) at: http://www.tuxedo.org/~esr/halloween.html Eric's comments include a reference to Squeak: "This prediction is of a piece with the author's earlier assertion that open-source development relies critically on design precedents and is unavoidably backward-looking. It's myopic -- apparently things like Python, Beowulf, and Squeak (to name just three of hundreds of innovative projects) don't show on his radar." Enjoy, Mike Wirth <usual disclaimers>

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Re: squeak hogs memory on linux?
by Greg Lewin 03 Nov '98

03 Nov '98

>Greg (or anyone else familiar with the problem), > >Have you been able to resolve this problem. I have been playing with >Squeak for a while on Win32, DOS, and HP-UX, but only recently I >reinstalled Linux on a Thinkpad. I am having the same problem with >Squeak 2.2 locking up. Top says it is using more than 90% of the CPU >(don't remember exacly how much memory it's using, but I have 40MB >installed). I am running kernel 2.0.34 (slackware) and wondering if I >need to upgrade. > It's better on RedHat 5.1 and Squeak 2.2 (was 5.0 and 1.3), but I still get similar trouble if I click on one of the buttons in "play with me 4". >Last time I had Linux loaded (on another PC) I was at kernel 1.1.59 or >something, so I was quite pleased at being in the 2.x ballpark. I >guess I didn't upgrate *far* enough :-). Does it really need a newer >kernel, or have you found another fix? I didn't get anywhere with my old kernel. > >BTW, I am running on a 486 and I couldn't get the compiled version of >Squeak 2.2 for Linux to run, so I downloaded the sources and >recompiled. At first the image seems to run fine, until I try to >update the code from the server (after setting my proxy server and >port). I get a socket timeout error. When I popup the menu and select >debug, I see the debugger, but when I click on the stack, the image >locks up. Any ideas? sorry! all my net access is from NT. -- Greg Lewin

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XP test cases and message semantics
by Bob Shafer 03 Nov '98

03 Nov '98

[ Travis mentions, in c.l.s, that XP test cases are written *before* the code is, and I'd rather reply here, in ramble-mode, with.... ] More importantly, the study of program correctness proofs has led to the discovery and elucidation of methods for developing programs. Basically, one attempts to develop a program and its proof hand-in-hand, with the proof ideas leading the way! -David Gries, in "The Science of Programming" (1981) Extreme Programming's test cases are "proof ideas", in effect. These "proof ideas" Gries is discussing evolved. A program is correct relative to its specification. A program is said, then, to satisfy its specification: A program p satisfies its specification s, if any client asking for s would be happy using p. (Sound like Eiffel?) A program can itself be seen as a specification: a program is a specification with no "non-algorithmic" components. This induces a notion of refinement between specifications, with the ultimate goal of refinement being to start with a (formal) specification and, through a series of small refinements, remove the non-algorithmic parts, resulting in a program. Calculi and methods of program refinement were developed. It seems to me that a Smalltalk message is a "non-algorithmic" specification, in the sense given above. A method satisfies/refines its message, within the context of the receiver. Now, a message is not exactly formal. Rather, a message is fuzzy-formal, to coin a phrase. It corresponds to a fuzzy concept, not a formal, concrete one. But that's a good thing, because that's what we think with: fuzzy concepts. The fuzzy is why Smalltalk is so cool. Isn't it? However, there are good reasons to constrain the fuzzy. The IRS is a good reason, in the context of a payroll system. XP test cases constrain the fuzzy, where it needs constraints, and nowhere else. Protocols constrain the fuzzy (in a fuzzy way). Typing constrains the fuzzy (to the point of throttling it, I'm guessing). One very neat thing about the fuzzy nature of messages: they are like natural language words in that while they don't necessarily have a precise meaning, they do have a fuzzy, shared meaning. Smalltalk: The programming language of common sense?

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