Beginners May 2010

beginners@lists.squeakfoundation.org

36 participants
28 discussions

addDeferredUIMessage: Documentation
by Sean P. DeNigris 14 May '10

14 May '10

I'm trying to add some documentation to addDeferredUIMessage:. What's a good summary on this method? I collected the following snippets from the web... If you want to run something that accesses the Morphic UI, even though you are not running from somewhere that the UI is in a sane state, you should normally use addDeferredUIMessage:. Otherwise, you can put Morphic into extremely confused states.... Per Ned Konz @ http://wiki.squeak.org/squeak/528: Deferred UI messages are processed in the middle of the Morphic event loop, just after responding to events, and before doing other step methods and displaying the world. Look for implementors of #addDeferredUIMessage:, look at the one in WorldState, look for senders of #deferredUIMessages, and you'll see WorldState>>runStepMethodsIn: which empties the queue. And it's called from doOneCycleNowFor: which is the body of the main Morphic event loop. Per http://wiki.squeak.org/squeak/5689: If you want to run something that accesses the Morphic UI, even though you are not running from somewhere that the UI is in a sane state, you should normally use addDeferredUIMessage:. Otherwise, you can put Morphic into extremely confused states.... Per Wilhelm K Schwab @ http://forum.world.st/Fwd-MouseOverHandler-td1300474.html#a1300474: provides a clean way to interact with the GUI from background threads Per http://www.visoracle.com/squeak/faq/containerless.html: As it is now, it's quite simple to put long-running computations in background threads; you just don't let the background threads call methods directly on Morphs. We have addDeferredUIMessage: to queue up action from the background threads for later execution in the UI thread during the next window cycle. Sean -- View this message in context: http://forum.world.st/addDeferredUIMessage-Documentation-tp2216105p2216105.… Sent from the Squeak - Beginners mailing list archive at Nabble.com.

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Re: [Newbies] (no subject)
by K. K. Subramaniam 13 May '10

13 May '10

On Monday 10 May 2010 12:01:58 am John Foster wrote: > My problem is how to display a fraction so it looks like a fraction, and > not like (2/5) + (7/8). I want the vinculum to be a horizontal line: > > 2 7 61 > --- + --- = ---- > 5 8 40 You could use a Column morph with its border width set to zero and fill style set to transparent color. You may have to override cell positioning to bottom right to get numbers to align right (halo for Column ->menu->layout->table layout->cell positioning -> bottom right). Replace Red and Green morphs with Text containing numerator and denominator. Set Yellow morph's color to black, length to 3 and width to the max (numerator width, denominator width). Create Column morphs for first fraction, +, second fraction, =, total fraction and put them into a Row Morph. HTH .. Subbu

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how do i initialize class variables?
by Avi Cohen 13 May '10

13 May '10

hello, can i initialize them like regulat object variable? if i do, doesn't it initalize the class variable at every object creation? thanks -- View this message in context: http://forum.world.st/how-do-i-initialize-class-variables-tp2195922p2195922… Sent from the Squeak - Beginners mailing list archive at Nabble.com.

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Smalltalk klass dokumentation ?
by Kommentaren 12 May '10

12 May '10

Hi! I wonder if there is any documentation that documents the different classes and methods available in Smalltalk. Preferably like javadoc in java. For example, somewhere you could go when you want to understand a code like the following (taken from the Laser-game tutorial at squeak). panel := RectangleMorph new borderWidth: 0; color: Color white; layoutPolicy: ProportionalLayout new. panel addMorph: self makeQuitGameButton fullFrame: (LayoutFrame fractions: (0@1 corner: 1@1) offsets: ( (20 @ (vertOffsetTop negated)) corner: (-20 @ (vertOffsetBtm negated)))). That is, you make a panel using the ProportionalLayout and then you add buttons to it. Here you need to know what the ProportionalLayout is and how the fractions and offsets parameters work to understand how the buttons are placed.

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Problems with Morphs on PluggableSystemWindow
by Mateusz Grotek 12 May '10

12 May '10

Hi. I have the following problem with morphs. I've used PluggableSystemWindow on which I've put some morphs. But after minimizing it morphs do not disappear. They still are visible below minimized window. What can I do to make them disappear while minimizing window?

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ProcessWrapper
by pascal.vollmer＠nexgo.de 11 May '10

11 May '10

Hi, A question about ProcessWrapper. I use ProcessWrapper to execute a Windows-application from Squeak. Everything is fine and reproducible as far as I activate this message sequence in the Workspace: ProcessWrapper new useStdout; startWithShellCommand: 'path_to_executable\executable.exe'; upToEnd; waitForExitFor: 5000; exitCode. As soon as I integrate the same stuff in a method, the image crashes. When I debug the situation I see that the crash occurs while performing ProcessWrapper>>upToEnd. Any clue what could be the problem here? Or how to investigate further? Kind regards, Pascal Pascal Vollmer Email: pascal.vollmer(a)ieee.org Traumziele - von Beschreibung bis Buchung jetzt kompakt auf den Reise-Seiten von Arcor.de! http://www.arcor.de/rd/footer.reise

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(no subject)
by John Foster 10 May '10

10 May '10

Hi everyone, I've been using Squeak to write little tools to help my students drill various maths skills. Since modern students have major issues working with fractions (due, I believe, to too much calculator too soon) I want to produce a morph that displays a simple arithmetic problem. The student attempts to solve the problem, and then clicks on the morph, which then displays the solution. If the student clicks on the morph again it shows a new (randomly selected) problem. I've used the idea with a few other types of problem quite successfully. My problem is how to display a fraction so it looks like a fraction, and not like (2/5) + (7/8). I want the vinculum to be a horizontal line: 2 7 61 --- + --- = ---- 5 8 40 Can anyone point me at example code on how to get things formatted nicely? It looks as if I have to somehow calculate how many pixels wide and high each character is, and place each character nicely individually, which seems like an insane amount of work to do something that seems like it should be straightforward. Should I have 5 text morphs imbedded in a rectangle morph, using automatic sizing and keeping track of the bounds of each so I can draw lines to put the vinculums in place, or is there a cleaner way that requires less management code? Things seem awfully messy catering for the different things that could come up (like 2/15, 15/2, 2/123 etc). Pointers to existing code would be ideal, so I can understand things, rather than just dropping a solution on me. Thanks in advance, John Foster.

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combining arrays.....?
by noobie 09 May '10

09 May '10

Hey, I can't figure out how to write a method to combine two arrays....for example.... #(1 2 3 4 5) combine: #(a b c) should return the array #(1 a 2 b 3 c 4 5). any help would be greatly appreciated. -- View this message in context: http://forum.world.st/combining-arrays-tp2124676p2124676.html Sent from the Squeak - Beginners mailing list archive at Nabble.com.

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Hello, and probably a bug.
by Mateusz Grotek 06 May '10

06 May '10

Hi. It's my first post on this list, so I'd like to say hi. Also please consider the following code: mrph:=Morph new. mrph on: #mouseDown send:#cr to: Transcript mrph click I get MessageNotUnderstood: UndefinedObject>>yellowButtonPressed Messages are: -->click-->mouseDown-->yellowButtonPressed Morph's #click method sends "self mouseDown: nil" but Morph's #mouseDown method do: "evt yellowButtonPressed", but evt is nil. Version is 4.1 md5sum of image: ffbd95f34e94dfdc5f18345c0b875f57 Squeak4.1.image

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Re: Teaching Smalltalk.
by Jerome Peace 06 May '10

06 May '10

Hi all, Okay, I wanted to take a shot too. I looked at the Gnu smalltalk version of the code and saw it was pretty good. I gave up trying to compete with it directly. Then I thought about how I would do the optimized version. I wanted brevity. Plus I wanted to show why I like squeak, the ability to make clear readable code. I usually practice code in a workspace before committing it to methods and such. So I ended up writing this as workspace code with the exception of adding a method to Integer which I would want it to have anyway. So the optimized version where you recognize that only the square doors are left open: | count doorEndsUp | count := 100 . doorEndsUp := [ :door | door isSquare ifTrue: [ ' Door ' , door , ' is open ' ] ifFalse: [ ' Door ' , door , ' is closed ' ] ] . 1 to: count do: [ :each | Transcript show: ( doorEndsUp value: each ) ; cr ] . "plus Integers now know how to tell if they are square ." Integer>>isSquare "True if our square root has no fraction" ^ self sqrt \\ 1 = 0 I needed to define #isSquare because it was not there already. Also it would go against my style to put the low level test directly in doorEndsUp doorEndsUp takes responsibility for producing the output string as the value of the door number. Then the main loop takes responsibility for knowing where the output line is to be put and providing a door number to each door. It is actually just a message to all the door numbers. The simulation version of the solution followed from the optimized version: | count doorEndsUp swing doors | count := 100 . doors := Array new: count withAll: false . doorEndsUp := [ :door | ( doors at: door ) ifTrue: [ ' Door ' , door , ' is open ' ] ifFalse: [ ' Door ' , door , ' is closed ' ] ] . swing := [ :each | doors at: each put: ( doors at: each ) not ] . 1 to: count do: [ :eachPass | ( eachPass to: count by: eachPass ) do: swing . Transcript show: ( doorEndsUp value: eachPass ) ; cr ] . Note we just had to change the predicate for doorEndsUp. Also to go along with the style we define swing to hide the details in the main routine. This makes it more readable. To one up the other examples we note that when a doors pass comes up, by the end of the pass the doors final fate is known. So we simply combine the output with the the pass. This makes for a very simple, compact way to represent the problem. Alright, now the itch is scratched. I await the restless coder who one ups me. Yours in curiosity and service, --Jerome Peace

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Beginners May 2010