Beginners January 2008

beginners@lists.squeakfoundation.org

63 participants
51 discussions

block in recursion, Any cure for that kind of situation?
by Hilaire Fernandes 23 Jan '08

23 Jan '08

I got an error "Attempt to evaluate a block that is already being evaluated", when I call in recursion a block like carre := [:s1 :s2 :s3 :s4 :n | n >0 ifTrue: [carre valueWithArguments: {(segment value: s1 value: s2). (segment value: s2 value: s3). (segment value: s3 value: s4). (segment value: s1 value: s4). n-1}]] Hilaire

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Getting NewCompiler/re-entrant blocks to work - Re: [Newbies] block in recursion, Any cure for that kind of situation?
by Marcin Tustin 23 Jan '08

23 Jan '08

Thanks. The approach that worked best by far was to load just NewCompilerLoader, then do: NewCompilerLoader new loadPackages. Then to correct syntax errors as they came up. The first error that wasn't a simple extra full-stop halted the recompilation process (because I couldn't fix it), but enabling the options mentioned meant that blocks are now fully reentrant. Excellent! On Jan 23, 2008 12:26 AM, Mathieu Suen <mathk.sue(a)gmail.com> wrote: > On Jan 23, 2008, at 1:00 AM, Marcin Tustin wrote: > > > So am I right in thinking that if I get newCompiler, blocks will > > work as I would expect them to (like lambdas)? > > > > If so, how do I get the most recent version? I remember there being > > something that has superceded squeakmap, but I can't seem to find it. > > You can find it on squeaksource. > http://www.squeaksource.com/NewCompiler.html > > You first need to load AST NewParser RefactoringEgine and SmaccRuntime. > In other to load them all you could use the NewCompilerLoader > availible one the NewCompiler squeaksource repository. > Simply invoke: > NewCompilerLoader new loadPackage. > > This will recompile the complete image using the NewCompiler. > > To avoid the recompilation you can look at the loadPackage method. > You could also load the NewCompiler throw the Universe browser. > > After loading the compiler you have 2 way to compile code. > > 1. Use the NewCompiler but don't make full block closure. (Preference > browser section compile #compileUseNewCompiler) > > In this mode the block still remain the same and temp are share > among the home context. That the reason why you could not invoke > recursively a block. > > 2. Enable the block closure. (Preference browser section compile > #compileBlocksAsClosures) > > With this preference the block while be transform in full block > closure. You could then recursively > invoke a block. Block while then create a environment to store > temps > whenever is needed. > > > HTH > Cheers, > > > > > > > > On Jan 22, 2008 11:42 PM, Ben Goetter <goetter(a)mazama.net> wrote: > > >This is a maintenance nightmare waiting to happen. Use a proper > > method call, > > > > Squeak Smalltalk blocks are just similar enough to Scheme lambdas > > that I still fall into this trap, too. > > > > (letrec ((carre (lambda (s1 s2 s3 s4 n) > > (if (> n 0) > > (carre (segment s1 s2) > > (segment s2 s3) > > (segment s3 s4) > > (segment s1 s4) > > (- n 1)))))) > > 'oops-must-remember-this-is-Squeak-not-Scheme) > > > > Ben > > _______________________________________________ > > Beginners mailing list > > Beginners(a)lists.squeakfoundation.org > > http://lists.squeakfoundation.org/mailman/listinfo/beginners > > > > _______________________________________________ > > Beginners mailing list > > Beginners(a)lists.squeakfoundation.org > > http://lists.squeakfoundation.org/mailman/listinfo/beginners > > Mth > > > > _______________________________________________ > Beginners mailing list > Beginners(a)lists.squeakfoundation.org > http://lists.squeakfoundation.org/mailman/listinfo/beginners >

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Re: [Newbies] Loading windows bitmap?
by Frank Urbach 21 Jan '08

21 Jan '08

Hi Blake, Try this k := SketchMorph fromFile: 'C:\Dokumente und Einstellungen\Baldsiefer\Eigene Dateien\Eigene Bilder\Beispiel.jpg'. k openInWorld. HTH Frank -------- Original Message -------- Subject: [Newbies] Loading windows bitmap? (21-Jan-2008 0:56) From: Blake <blake(a)kingdomrpg.com> To: frank.urbach(a)schmees.com > I'm trying to load an external (windows) bitmap and set a sketchmorph (or > imagemorph) to display. There's a lot of stuff to cycle through images in > sketchmorph but I don't see how to load something. I've been trying: > > i := ImageMorph new. > f := FileStream readOnlyFileNamed: 'C:\Windows\WinNT.BMP'. > i image: (Bitmap newFromStream: f). > World addMorph: i. > > But no joy. > _______________________________________________ > Beginners mailing list > Beginners(a)lists.squeakfoundation.org > http://lists.squeakfoundation.org/mailman/listinfo/beginners Edelstahlwerke Schmees GmbH Geschäftsleitung Clemens Schmees Sitz D-01796 Pirna Handelsregister Dresden HRB 54 E-Mail: es.la(a)schmees.com WEB: www.schmees.com Diese E-Mail enthält vertrauliche und/oder rechtlich geschützte Informationen. Wenn Sie nicht der richtige Adressat sind oder diese E-Mail irrtümlich erhalten haben, informieren Sie bitte sofort den Absender und vernichten Sie diese Mail. Das unerlaubte Kopieren sowie die unbefugte Weitergabe dieser Mail ist nicht gestattet. This e-mail may contain confidental and/or privileged information. If you are not intended recipient or have received this e-mail in error, please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is stictly forbidden.

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Loading windows bitmap?
by Blake 21 Jan '08

21 Jan '08

I'm trying to load an external (windows) bitmap and set a sketchmorph (or imagemorph) to display. There's a lot of stuff to cycle through images in sketchmorph but I don't see how to load something. I've been trying: i := ImageMorph new. f := FileStream readOnlyFileNamed: 'C:\Windows\WinNT.BMP'. i image: (Bitmap newFromStream: f). World addMorph: i. But no joy.

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Overriding methods
by Blake 21 Jan '08

21 Jan '08

Hey, all: I figure this is a beginner question. I get a big warning when I override certain methods. (Class methods?) For example, if I want to set up the "contractless" part of my object, I do so by overriding #basicNew, and then setting the values that allow the instance of the object to function. This seems perfectly normal and reasonable, but I get this big warning about how terrible it might be. I not even 100% clear on how it could be so terrible beyond that particular class. (I guess it's possible in this way to create an object that destabilizes the system?) Am I doing this wrong/non-optimally? (Maybe I should be overriding #new instead of #basicNew, but I get the same dire warning for #new). ===Blake=== P.S. Seeing if this goes through; last message I sent warned me that I wasn't on the mailing list.

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Re: [Newbies] Squeak for robot imaging and scientific applications
by Ken G. Brown 20 Jan '08

20 Jan '08

Here are some more or less Squeak robotics related links I've saved, perhaps they will be of some use: <http://sky.fit.qut.edu.au/~sitte/> <http://www.wifibot.com/> <http://wiki.itolab.com/wiki.cgi?page=About+Defart> <http://www.hawcenter.org/> <http://www.robotis.com/html/sub.php?sub=1&menu=3> This one I think was for a wiki that Serge Stinckwich had going but does not appear to work now. <http://www.iutc3.unicaen.fr/serge/SqueakBot> Perhaps you can contact him about it via <http://www.iutc3.unicaen.fr/c3/SergeStinckwich>. Ken G. Brown At 7:55 AM -0800 1/20/08, beginners-request(a)lists.squeakfoundation.org apparently wrote: >Date: Sun, 20 Jan 2008 05:02:26 -0800 >From: "Robert F. Scheer" <rfscheer(a)speakeasy.net> >Subject: >To: A friendly "place to get answers to even the most basic questions > about Squeak." <beginners(a)lists.squeakfoundation.org> >Message-ID: <1200834146.6839.51.camel@ferdoom> >Content-Type: text/plain; charset=utf-8 > > >On Sun, 2008-01-20 at 13:29 +0100, Herbert Knig wrote: >> Hello Robert, >> >> RFS> I am using Squeak to control a robot, specifically a RoboMagellan >> RFS> outdoor navigating robot. Pretty soon it will be important to confront >> RFS> how to implement the computer vision on this robot. The OS is Linux. >> >> Jon Hylands is doing robot control in Squeak, see www.huv.com and >> several others do too. >> > >Thanks Herbert, yes, I already get a lot of help directly from Jon and >that's how I know about sockets and how to interface to packages like >OpenCV that is written in C++. > >So far it looks like the practical approach involves using an external >vision system that you interface Squeak to. So you end up coding in C/C >++ or conceivably some other language like Python for that part of the >system. > >Maybe this question requires advanced answers and should be posed on the >dev forum but it's really a newbie question and is very important for >anyone thinking about using Squeak in a science or engineering >context. > >> You will find information in the archives of squeak dev. > >I'll look through the archives for this discussion. > >- Robert

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Morphic - How to animate without defining #step ?
by Oscar Nierstrasz 20 Jan '08

20 Jan '08

Hi Folks, I have been struggling with Morphic animation. I would like to animate some different algorithms that compute solutions to various puzzles. (It is for an introduction to Squeak for high school students.) Normally animations in Morphic are done by defining the #step method. But in this case I want to animate various stages of an algorithm. I cannot split the algorithm into bits and pieces that can be evaluated by #step without destroying the algorithm. I have tried to update the morph from within the algorithm (i.e., by changing the color of various submorphs) but this does not work. I only see the final state. Can anyone tell me if what I want to do is even possible? Any pointers to some existing application that does this? If you want to see what I am trying to do, look at Mazemorph>>shortestPath in http://www.squeaksource.com/SOI.html MazeMorph soi openInWorld; shortestPath There is a simple BoardMorph made up of CellMorphs, specialized to search through a maze and find the shortest path. I would like to animate the depth-first searching, but I can only display the final state. There are other algorithms I would like to animate, but this is a typical case. (I thought of evaluating the algorithm as a separate process, with pauses at key points, and using #step to continue to the next pause, but that seems like overkill to me. There must be an easier way ...) - on

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Squeak for robot imaging and scientific applications
by Robert F. Scheer 20 Jan '08

20 Jan '08

I am using Squeak to control a robot, specifically a RoboMagellan outdoor navigating robot. Pretty soon it will be important to confront how to implement the computer vision on this robot. The OS is Linux. One way to do this is to use an external vision system such as RoboRealm running under MS Windows and communicate between the Squeak controller and the vision system with sockets. I'll probably do something like that but it's only a short-term solution. RoboRealm is a proprietary, closed-source application that won't be able to do something I'll want to do, perhaps something like figuring out how far the robot travels between video frames by comparing the movement of "interest points". At that point I will want some type of vision or imaging library directly accessible to Squeak. Python has an imaging library called Python Imaging Library. This is one of the strongest justifications some people use to write their entire robot code in Python in the first place. Likewise, Python has the SciPy library, which provides a large set of tools for signal and image processing, as well as linear algebra, optimization, statistics and so forth. For example, suppose I wanted to write a Kalman or other probabilistic filter for "fusing" inputs from a cameras, inertial sensors, wheel encoders and so forth. In Python, the matrix operations for doing the math would be simple calls. How would you approach these imaging and quasi-scientific issues in Squeak? Would you always end up using external packages and making interfaces to them through sockets or through special primitives in a custom VM? Thanks for your thoughts. - Robert

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Getting a list of files from a folder
by Marcus Strehlow 20 Jan '08

20 Jan '08

Hi all, I am trying to figure out how a list of files of a given directory can be put into a PluggableListMorph. It is important to me to find this out as I am trying to create something that works with reading the content of files. Can you guys help me on this? Thanks, Marcus

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Object clone
by Jakub 17 Jan '08

17 Jan '08

hello, i want do i want set var a as all instance vars of b. Something s clone - coppy of one object. I look for clone command in SBE book but i found nothing. Thnx. -- Jakub.

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Beginners January 2008