Squeak-dev April 1999

squeak-dev@lists.squeakfoundation.org

130 participants
319 discussions

Re: Calling methods from primitives
by Stephen Pope 29 Apr '99

29 Apr '99

Stephen Pair wrote: > > Does anyone how to invoke a method on an object from within a primitive? Is > there a way? There's no direct and simple way to handle arbitrary "call-backs" from the VM into Smalltalk. I do it via Semaphores. You can easily register a semaphore as an external object, then signal it from a primitive. If you have a Smalltalk process waiting on the semaphore, it can do whatever it wants -- send a message, call another primitive, etc. -- stp Stephen Travis Pope stp(a)create.ucsb.edu http://www.create.ucsb.edu/~stp/

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Flash Player Example
by Dan Ingalls 29 Apr '99

29 Apr '99

Folks - It has come to my attention that the Flash example in the welcome window doesn't work as presented. It says to execute... (...) processFile. This does in fact work, and it is wonderful what it does, but you would never know from watching it, except to wonder if it is possibly a demonstration of Squeak's progress bar. It will be much more enlightening and entertaining to execute instead... (...) processFile startPlaying openInWorld. Enjoy - Dan

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STP12 Goodies for Squeak 2.4b Available
by Stephen Pope 29 Apr '99

29 Apr '99

Hello all, I've up-loaded the new release of the STP12 goodies for Squeak 2.4b to ftp://ftp.create.ucsb.edu/pub/Squeak/Goodies/STP12 The new changes include: All STP12 tools (launcher, package browser, outliner) run in Morphic STP12 tools added to Morphic flaps Numerous small system fixes For more info, see http://www.create.ucsb.edu/squeak/STP12.html. The FTP site has the packaged sources and file-in script in BinHexed StuffIt and compressed tar formats. There's also a pre-built 2.4b image/changes files and an un-packed file tree of the sources. As in the past, I've written a new source file after building the STP12 image, so if you up-load the image, be sure to get SqueakV2.4.sources as well. Comments/fixes are invited... -- stp Stephen Travis Pope stp(a)create.ucsb.edu http://www.create.ucsb.edu/~stp/

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Re: Help manage Squeak info??
by stan＠stanheckman.com 29 Apr '99

29 Apr '99

I'm willing to commit an hour a week into copying the good stuff from the mailing list onto the Swiki. -- Stan

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Re: How to add a class and instance in SystemBrower
by Joshua Gargus 29 Apr '99

29 Apr '99

Hi century, Go to www.squeak.org The second link on the page is appropriately labelled 'Tutorials'. There are two tutorials that can be reached from the link. They are both good, but the second has some screenshots that will walk you through the process. Have fun, Josh On Thu, 29 Apr 1999, century wrote: > Thanks > On Thu, 29 Apr 1999, century wrote: > Thanks >

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Re: Publish-Subscribe, Weak Arrays and Garbage Collection...
by James Foster 29 Apr '99

29 Apr '99

An out-of-bounds error sounds like you are iterating over a collection that is being modified (perhaps, as you suggest, by GC activity). Rather than get involved with semaphores, I'd suggest iterating over copies of collections. For example, modify PostOffice>>#incoming:from: to send #keysAndValuesDo: to a copy of <subscribers>. But then I've only given this a couple minutes thought, and I don't have a Squeak image up to try your code, so take this for what it is worth! James Foster -----Original Message----- From: Peter Smet <peter.smet(a)flinders.edu.au> To: squeak(a)cs.uiuc.edu <squeak(a)cs.uiuc.edu> Date: Thursday, April 29, 1999 12:46 AM Subject: Publish-Subscribe, Weak Arrays and Garbage Collection... >Hi all, > >I have been trying to implement a publish subscribe mechanism along >the lines of Dolphin and VW. With it, any object can trigger events such as > >Transcript trigger: #bang. >an interest in events is registered by the message: >Transcript when: #bang send: #run to: self >etc. > >The disadvantage of publish subscribe is that you must explicitly deregister >objects from the mechanism for them to be garbage collected. >I have tried to get around this by using weakKeyDictionaries to hold both >the publishers and the subscribers. If there are no remaining references to >either the publisher or the subscriber, these will be garbage collected, and >no events will be passed to these deceased objects. This certainly makes >everything a lot easier to maintain. > >Everything seems to be working as planned. However, if I run some processes >where lots of temporary objects are created and many messages passed, >sooner or later some kind of synchronization problems occur. The normal >pattern >is that a WeakKeyDictionary attempts to access an array at an out of bounds >index. I suspect that the finalization process is "stealing" my weakDict >keys when >objects are garbage collected. This error can be created by running >PostOffice start. PostOffice stop will halt the thread. >PostOffice initialize clears the dictionaries with publishers/subscribers. > >So my questions are: >Is this a synchronization problem with the FinalizationProcess in WeakArray? >is the WeakKeyDictionary class process safe, or how can I make it so? >Do I need to integrate my (PostOffice) class with the FinalizationSemaphore >or FinalizationLock of class WeakArray - how would I do this, how do I >access >these semaphores? > >A change set is attached. Some of the code is in Object, and Message, >under "publish-subscribe" > >Using 2.4b under win NT SP3. Any insights greatly appreciated. > >Peter > > > > > >

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Progress on Documentation
by Dan Ingalls 29 Apr '99

29 Apr '99

Folks - Paul McCullough and I are finally making some progress on the Squeak documentation Swiki pages http://minnow.cc.gatech.edu/SqueakDoc.1 We still have a long way to go, but you might want to visit from time to time and see what you like and don't like. Speaking for myself (and Paul probably feels the same), I welcome any criticisms, especially those in the form of suggested insertions, deletions, or replacements. It will reduce traffic here if you could address such contributions directly to Paul and me, rather than replying to the list in general. Enjoy - Dan

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Publish-Subscribe, Weak Arrays and Garbage Collection...
by Peter Smet 29 Apr '99

29 Apr '99

Hi all, I have been trying to implement a publish subscribe mechanism along the lines of Dolphin and VW. With it, any object can trigger events such as Transcript trigger: #bang. an interest in events is registered by the message: Transcript when: #bang send: #run to: self etc. The disadvantage of publish subscribe is that you must explicitly deregister objects from the mechanism for them to be garbage collected. I have tried to get around this by using weakKeyDictionaries to hold both the publishers and the subscribers. If there are no remaining references to either the publisher or the subscriber, these will be garbage collected, and no events will be passed to these deceased objects. This certainly makes everything a lot easier to maintain. Everything seems to be working as planned. However, if I run some processes where lots of temporary objects are created and many messages passed, sooner or later some kind of synchronization problems occur. The normal pattern is that a WeakKeyDictionary attempts to access an array at an out of bounds index. I suspect that the finalization process is "stealing" my weakDict keys when objects are garbage collected. This error can be created by running PostOffice start. PostOffice stop will halt the thread. PostOffice initialize clears the dictionaries with publishers/subscribers. So my questions are: Is this a synchronization problem with the FinalizationProcess in WeakArray? is the WeakKeyDictionary class process safe, or how can I make it so? Do I need to integrate my (PostOffice) class with the FinalizationSemaphore or FinalizationLock of class WeakArray - how would I do this, how do I access these semaphores? A change set is attached. Some of the code is in Object, and Message, under "publish-subscribe" Using 2.4b under win NT SP3. Any insights greatly appreciated. Peter Content-Type: application/octet-stream; name="Publish-Subscribe.29Apr244pm.cs" Content-Disposition: attachment; filename="Publish-Subscribe.29Apr244pm.cs" Attachment converted: Anon:Publish-Subscribe.29Apr244pm.cs (????/----) (000098AD)

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QuickTime in Squeak
by Mark Guzdial 29 Apr '99

29 Apr '99

I remember reading that someone on the list was working on a plugin primitive to allow QuickTime video to be displayed on the Squeak Display. I just read that QuickTime 4 (beta available off http://www.apple.com/quicktime/) includes MP3 playback. How hard would it be to get Squeak to play generic files through QuickTime (on platforms that support it)? Admittedly, a Squeak-based MP3 decoder would be more fun, and I do understand that MP3 isn't such great quality -- but there's a lot of MP3 files out there, and playing with them in Squeak would be cool. Mark -------------------------- Mark Guzdial : Georgia Tech : College of Computing : Atlanta, GA 30332-0280 (404) 894-5618 : Fax (404) 894-0673 : guzdial(a)cc.gatech.edu http://www.cc.gatech.edu/gvu/people/Faculty/Mark.Guzdial.html

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RE: Scrolling Preferences
by Norton, Chris 29 Apr '99

29 Apr '99

> > On Tue, 27 Apr 1999, Hans-Martin Mosner wrote: > > I would also like the scrolling framework to be more modularized. > I agree with you Hans & Bert. Here's how Scrolling is represented in my VisualSmalltalk Enterprise hierarchy. Of course, we don't have a generic native Window class (yet) in Squeak, but you get the general idea. There are a number of generic uses for objects that have a list (with a minimum and maximum) that can be traversed in the way that the traditional scroll bar does. Objects like progress indicators, spin boxes and scroll bars are very similar in nature. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Object Window (handle rectangle children parent owner style graphicsTool properties) SubPane (handlers topCorner framingBlock curFont menu popup id) ControlPane (value label) RangeControl (min max lineIncrement) PagedRangeControl (pageIncrement) ScrollBar WBHorizontalScrollBar WBVerticalScrollBar TrackBar (ticks) ProgressBar UpDown (buddy) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Cheers! ---==> Chris

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