Squeak-dev July 2002

squeak-dev@lists.squeakfoundation.org

205 participants
393 discussions

Re: New Random Number Generator
by Mark4Flies＠aol.com 12 Aug '02

12 Aug '02

<< OK, I have a working trivial plugin for this that just does a 30bit int for now. >> I do not understand what is different about working with 30 bit integers as opposed to the 32 bit version I started with? << Seems to work ok - making a bag of 1000 values suggests it at least does a tolerable job. Though it does bother me a bit that in a whole load of tests I've not seen any number with less than a half-dozen digits. I'll let you numerics fanatics worry about that part. >> You mean that all of the sample numbers have at least six decimal digits? << So what sorts of values would be useful? Is just a 30bit int ok with any further cleverness being done in the image? >> I am not sure if the desirable properties of the Mersenne Twister are preserved if we drop down from 32 bit words. I was hoping to duplicate the algorithm exactly. (Note I said "I", not "you" !) For casual use, it may not be any better or worse than the current generator. For serious use, though, it should reproduce the C program. If it does not, then one suspects that other properties are lost, too. -Mark

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The car script
by subroto mukherjee 12 Aug '02

12 Aug '02

Hello All, I'm a new Squeak enthusiast & at present i'm doing my University project, which involves developing an enhanced version of the racing car game shown in Squeak. I cant find enough reference material to start programming in Squeak. My application involves controllong the car using the keys in the keyboard. Any ideas ?

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[BUG?] - ScheduledControllers screenController openMorphicProject
by Magistrello Alejandro (SFA) 04 Aug '02

04 Aug '02

Hi I evaluate: ScheduledControllers screenController openMorphicProject "this is in the useful expresions workspace" you'll have a MessageNotUnderstood: addFirst: error, it seems like the ControlManager was not initialized, i changed the "ControlManager >>schedulePassive: aController" method, and i get the attached walkback. Is this a bug? the ScheduledControllers is never initialized? Alejandro ---------------------------------------------------------- the method changed: ControlManager >>schedulePassive: aController "Make aController be scheduled as a scheduled controller, but not the active one. Put it at the beginning of the ordered collection of controllers." scheduledControllers isNil ifTrue: [scheduledControllers _ OrderedCollection with: aController] ifFalse: [scheduledControllers addFirst: aController] ---------------------------------------------------------- <<SqueakDebug.log>>

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Re: Animorphic ST (Strongtalk) released!
by David Griswold 04 Aug '02

04 Aug '02

Hi Stefan and Andreas, Sorry for the late reply- I've been offline for the last few days. Several people including Andreas Raab and Stefan Aust were discussing the odd signature for the #-> message in the Strongtalk system. I'll explain the situation in a fair amount of detail for those who are interested, since this sort of example illuminates the kind of interesting issues involved in typing the Smalltalk libraries. The Strongtalk libraries have the -> signature as: -> other <Y def> ^<VarAssoc[X,Y]> {where X is receiverType} Andreas thought this was difficult to understand. In fact, if you know the type system, it is quite easy to understand; it means what it almost literally says; X is the type of the receiver known at the send site. What *is* difficult is to understand why it is that way and not some other way. Stefan asked why it could not have been written using the Self type, which we could do like this, without an inference clause: -> other <Y def> ^<VarAssoc[Self,Y]> The reason I didn't use that signature is that it would not be typesafe, because you can only use Self in 'covariant' positions in type signatures (crudely, places that return Self, not take it as an argument), if you want subtyping to work. The issue is subtle, and other type systems get around this sort of thing by just not having a Self type or generics, the combination of which requires you to understand this issue, which affects *any* type system that has subtyping. The issue is that VarAssoc is the protocol for *mutable* associations (vs. Assoc, which is the read-only protocol), which means that Self would be the argument type for the #key: message. If we allowed that, we could easily violate typesafety by passing it somewhere that a weaker type for Self was know (since Self automatically becomes more specific or general as necessary via inheritance), and then storing an invalid value into the key of the association. That is tricky to think about, but that is exactly what a type system does for you- it will tell you if it isn't safe, even if it's too complicated for you to think about. Now, this whole issue can be avoided if you just write: -> other <Y def> ^<Assoc[Self,Y]> which is perfectly typesafe, easy to read and understand, and valid in Strongtalk. Note the difference: this time I used Assoc, the read-only protocol, instead of VarAssoc, which includes the mutation operations. Since the association that is returned is read-only, it becomes safe to do this. Why didn't I use this simpler, more readable way of writing the message? I could have, but here was my reasoning: in code that is not heavily reused, these subtleties don't matter much, and that signature would be fine. But the messages in Object are used all over the place, and so a slightly more complicated signature that is more flexible seemed preferable. #-> is used to allocate associations, and the caller may well want to mutate that association after it was created. In any other type system, this would leave you stuck- you wouldn't be able to write the signature safely and still use the VarAssoc protocol. But there is a way to do it in Strongtalk, and I used it. Using an inference clause to 'infer' the receiver type, instead of using Self, is a standard, easy way to get around the limitations on use of Self. You will see it used in various places throughout the Strongtalk libraries: -> other <Y def> ^<VarAssoc[X,Y]> {where X is receiverType} Whenever you see something like this, just think this: an inferred receiverType is just like Self, *except* that it is effectively frozen (as the type known for the receiver at the call site, which is all the caller cares about, after all). Because it is frozen, all the tricky issues about where you can put Self just go away! Thus, we have found a way of writing a *flexible* piece of code (you can mutate the returned association), at the cost of this standard typing trick. This kind of thing quickly becomes easy if you use the type system all the time. Now, most users don't care about this kind of thing- they just want to understand the signature. You folks are reading this without the benefit of any experience using the type system, and without any documentation, which is a big handicap. I would claim that with just a tiny bit more experience, the signature is very easy to understand- the hard thing is understanding *why* it is that way. And only the person writing it really needs to think about that- the user can just use it, and the type system will give him the flexibility that the writer of the signature designed into it. If you are writing code and you don't want to think about this sort of thing, that's fine- you'll just have slightly less flexible code. It's much easier to write a type system that doesn't have these kind of issues, but the cost becomes a much more rigid type system (that in this example wouldn't let you mutate the returned association). This is an example of the kind of flexibility that we went to great pains to build into Strongtalk. It also illustrates how much thought went into the library design. Lest you think that this is a insignificant issue, a similar kind of design is essential for making it possible to type extremely difficult things like coercive arithmetic in the numeric hierarchy. Once again, you can just use it: it will act like you expect it to, even if you don't understand why it is that way. Regards, -Dave > From: Stefan Matthias Aust <sma(a)4plus4.de> > Subject: Re: Animorphic ST (Strongtalk) released! > Date: Sat, 20 Jul 2002 19:49:06 +0200 > > Andreas Raab wrote: > > > I found the type-system the most unnatural part about StrongTalk. > > For me, Strongtalk *is* the typesystem. It's nice, if the Animorphic ST > release is also fast, but IMHO the static type system is the more > interesting part. > > > It > > feels displaced and if you look at methods like "->" in Object you can > > see that there are some rather nasty complexities associated with it > > (not to mention readability issues). > > One can always argue about syntax. That's something you have to get > used to. All it says is that an Association's type is created from the > receiver and the parameter type. I don't understand why that isn't > written as > > -> other <Y def> ^<Association[Self, Y]> > > Instead of <Y def>, I might prefer 'Y. I once saw a Smalltalk dialect > which used {} instead of <> to declare types. That could be more readable. > > However, types don't become easier just by not writing them down... You > have to understand them to program. > > >>In Smalltalk (without types) no tool can exactly know the type of an > >>expression and code completion (with is IMHO the best > >>productivity tool of a modern IDE) cannot offer a valid > >>selection of applicable method names. > > > > That has been said many times and yet, I disagree. To the best of my > > knowledge nobody has ever tried to build a simple type inference system > > Perhaps, because it wont't work? > > > which just goes along with you as you are writing code and tries to > > discover what the types might be. > > Just a little bit of type inferrence doesn't work. Once, I tried it and > also had some discussions with somebody who thought about writing is > master thesis about this topic and we finally agreed upon that you'd > need either a full features type system or stay with no types at all. > > > Name completion and other utilities > > can even be used to tell such a type inference system about what types > > of certain objects are and I still think that you should be able to > > trivially figure out the types for 90% of the system > > someMethod: param > param . > > Okay, please tell me the methods applicable at the "." ? That's > impossile if you don't want to show *all* method names of the system - > which are probably 8000-10000. > > Code completion is IMHO the most important and best way to learn a class > library. VBA is a good example. Using the simple built-in IDE of MS > Word, I can script the whole program without much problems, just by some > guessing and the code completion. > > > I would hope that some better syntax can be found than > > is currently in both StrongTalk and SmallScript. > > Here, I agree. > > > But of course you do realize that *optional* types > > Sure, but it wouldn't be Smalltalk if you couldn't simply make the > optional mandatory and set the requirement of type in your project. > > In addition, I could document my assumption by annotation types which > would be then checked by the system and eventually get a better > documented, well formed program. > > > bye > -- > Stefan Matthias Aust // > www.3plus4software.de // Inter Deum Et Diabolum Semper Musica Est > > >

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[BUG?] weird behaviour of MVC in Squeak 3.2
by Boris Gaertner 03 Aug '02

03 Aug '02

On windows 98 the new Squeak 3.2 exhibits a quite strange behaviour when a debugger is opened in the MVC environment. Please try this. 1. create and enter an mvc project. 2. open a class hierarchy browser. 3. select StringHolder>>browseVersions. ( a lot of other methods would do as well. ) 4. Insert the statement self halt. at the beginning of the method and save the method with "accept" 5. Now, move the mouse into the method names view and select "versions" 6. a small red window with title "Halt" and three buttons is opened. Press the button "Resume" 7. a blue (or violet?) VersionsBrowser is opened. It flashes when it is opened and this detail is maybe important. 8. select a version. I see the method text displayed for a very short time, then the text view is empty again. There are also other weird effects (on my computer at least) *the system menue shows unusual behavior. *When the mouse pointer leases the versions brwoser and then enters it again, it crosses the window border. When it does, the curser changes to a "drag window border" symbol. That symbol does not vanish again when the mouse pointer is inside the versions browser. After a lot of nonsensical actions with the mouse Squeak seemingly comes back to normal bahaviour. I saw these strange things also in a 3.2 alpha (last update: 4599) with the virtual machine Squeak 3.2.2 VM (release candidate) from May 26 2002 Compiler: gcc 2.95.2 19991024 (release) I think that something with the process switching or scheduling goes wrong, but until now I have no idea what it is. Are there others out there that can confirm my observations? Have you any idea what I can do to better the situation? Greetings Boris

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Re: Progrmaming in Bytecode?
by Jon Hylands 02 Aug '02

02 Aug '02

At Wednesday, 31 July 2002, you wrote: >I know this may sound sadistic, but how could I go about programming in >Smalltalk bytecode, directly? I've seen assemblers for Java, that do the >same job as assemblers for native CPUs. I imagine such a tool doesn't >exist for SMalltalk at this time, but perhaps it wouldn't be hard to put >one together in my quest to play with bytecode. One of the projects I did a while ago was writing PIC/Smalltalk, which basically is a Slang-style translater that translates Smalltalk source code into PIC assembler. PIC chips are tiny 8-bit RISC embedded micro-controllers (www.microchip.com), with miniscule amounts of memory (program memory measured in single-digit kilobytes and RAM between 50 and 500 bytes). If you want to work at a low level with Smalltalk, doing stuff like that is fun and useful as well. And of course it works in Squeak, although its been a while since I did anything with it. http://www.huv.com/smalltalk for more details... Later, Jon -------------------------------------------------------------- Jon Hylands Jon(a)huv.com http://www.huv.com/jon Project: Micro Seeker (Micro Autonomous Underwater Vehicle) http://www.huv.com

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[IMPORTANT - well, I think so] SqueakMap first appearance!
by goran.hultgren＠bluefish.se 02 Aug '02

02 Aug '02

Hi all! In my BIG QUEST to bring ORDER to the Squeak universe I am hacking away furiously on SqueakMap. I currently have SqueakMap up and running "somewhat working" on my development machine: http://marvin.bluefish.se:8000/sm Feel free to check it out (though remember I am hacking on it at the same time). Right now you can: - Read the four help pages on SqueakMap/packages/repositories and categories. Give me feedback! - Play around registering and editing packages and repositories. Remember that you are only testing - nothing will be kept around yet! - List registered packages and repositories. Note that: - Categories are not yet entered when registering/editing packages. Otherwise it is complete but I will add some more field validation like syntax checks and filtering out naughty HTML. - Browsing packages by category is not yet implemented, coming any hour... - There is no searching yet. I want to integrate Scotts search engine but I need to look into that. - Scamper might not work because I don't think it supports cookies or POSTs. Am I wrong? My plan for the next days is to fix the most important stuff like (off the top of my head): -Add browsing by category and selecting categories when registering packages. -Ensure uniqueness of package and repository names. -Add some syntactic validation and naughty HTML filtering. -Make sure the remote synching of a "slave map" works. This is actually the cool part of it all - to be able to maintain a synchronized slave map in YOUR OWN image for fast searching of packages and modules. The web front is just a nice "last resort". -Add email reminders of passwords. :-) -Add some administration facilities for the categories. After that it should be ready for more serious testing. Reply to the list with all your feedback. It is important that we agree on the fields of the packages and repositories. regards, Göran

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[BUG] [FIX][?] 3.2 -- showBoundsInHalo preference disables dismiss halo button.
by Ned Konz 02 Aug '02

02 Aug '02

This is still a bug in the shipping version. The fix (which I think someone else suggested) appears to be to remove the method HaloMorph>>bounds: Can anyone tell me whether this is the *correct* fix? ---------- Forwarded Message ---------- Subject: [BUG] 3.2g -- showBoundsInHalo preference disables dismiss halo button. Date: Sat, 23 Feb 2002 13:09:47 -0800 From: Ned Konz <ned(a)bike-nomad.com> To: squeak-dev(a)lists.squeakfoundation.org If you turn the showBoundsInHalo pref on, you can't delete Morphs using the dismiss (pink X) halo button. 3.2g - 4743. -- Ned Konz currently: Stanwood, WA email: ned(a)bike-nomad.com homepage: http://bike-nomad.com ------------------------------------------------------- -- Ned Konz http://bike-nomad.com GPG key ID: BEEA7EFE

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Has anyone bothered to check out SqueakMap?
by Göran Hultgren 01 Aug '02

01 Aug '02

Hi guys! I don't want to NAG, but have anybody at least looked at SqueakMap running in part on: http://marvin.bluefish.se:8000/sm Do note that SqueakMap is NOT only for the new modules system - far from it in fact. Let me reiterate in short: - A master server will run SqueakMap on squeakfoundation.org (or similar) - It will have the webUI you can see above (but prettier and with more functions) - You will be able to search (using Scott's engine), browse (similar to Yahoo or GNOME software map), register and update Squeak packages and Module repositories. - A Squeak package is simply a piece of published Squeak software. It does not need to be packaged as a 3.3alpha Module. - A module repository is more or less a "mount point" in the global virtual module namespace that the new modules system introduces. - You will also be able to run your own "local" slave map in your image and synchronize it really efficiently using simple HTTP/gzip (straight through firewalls and a modem will do) with the master. - The slave map (and the master) keeps it's state in one simple logfile using chunkformat. Simple, efficient and since the map opens/closes on each operation it is always written to disk. - You will have a nice MVC/Morphic browser to do all these functions inside Squeak. - You will be able to install any module (as in the new modules system) in the world by just knowing it's module path since the slave map will be able to figure out which repository the module resides in. Well, it will not bring World Peace but it sure will be an important piece of the Squeak community so PLEASE... Take a look, read the help pages and give me some FEEDBACK. regards, Göran Göran Hultgren, goran.hultgren(a)bluefish.se GSM: +46 70 3933950, http://www.bluefish.se \"Department of Redundancy department.\" -- ThinkGeek

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Problem with 3.2 Solaris tarball
by Dwight Wilson 01 Aug '02

01 Aug '02

Hi, I just grabbed the file /Smalltalk/Squeak/3.2/unix-linux/Squeak-3.2-sparc-sun-solaris2.8-3.2-4.tar.gz from st.cs.uiuc.edu. gunzip complains about an unexpected end of file. Yes, I made sure that I did a binary transfer. -Dwight

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