Squeak-dev February 1998

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110 participants
320 discussions

Difference between views, viewports, forms, canvases and windows
by Philippe de Rochambeau 03 Feb '98

03 Feb '98

The difference between views, viewports, forms, canvases, and windows is not too clear in my mind and the Squeak online documentation does not make it clearer. Could someone please enlighten me on the matter? Would you use a view, a viewport, a form, a canvas, or a window, if you simply wanted to draw a shape in a window (separate from the Workspace) using a Pen? Many thanks. Philippe de Rochambeau

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CaretForm mystery
by Matthew Rosen 03 Feb '98

03 Feb '98

I'm _very_ puzzled about a strange little critter in the Squeak 1.30 image (and earlier images for that matter). I ran across it in the method: Paragraph>>caretFormForDepth: The top part of the method reads as follows: caretFormForDepth: depth "Return a caret form for the given depth." "(Paragraph new caretFormForDepth: Display depth) displayOn: Display at: 0@0 rule: Form reverse" | box f bb map | box _ CaretForm boundingBox. f _ Form extent: box extent depth: depth. ....and so on... The puzzling critter is CaretForm. It looks like it should be a class variable, but it is not defined as one in Paragraph or any of its superclasses. It is not a class instance variable either. It doesn't show up as a global in the Smalltalk dictionary. The explain message says that it can't explain it. Selecting CaretForm and inspecting it tells you that it is an undeclared variable, and suggests some corrected spellings, but no object for it. Despite all of this, you can run the example in the method comment, and it works perfectly! You can step through with a debugger, and CaretForm responds happily to methods intended for Form instances. Of course, now it shows up in my Undeclared dictionary, and there are (naturally) no references to it when you ask. Granted, I only have eight years of Smalltalk experience, but even I know that something outside the normal Smalltalk rules is happening here. Please, I want to sleep nights again. Can someone shed light on this mysterious phenomena? -- Matt Rosen, Director for Technical Services San Joaquin Delta College

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Re: CaretForm mystery
by Tim Olson 03 Feb '98

03 Feb '98

Matt wrote: >The puzzling critter is CaretForm. > >It looks like it should be a class variable, but it is not defined as >one in Paragraph or any of its superclasses. It is not a class instance >variable either. It doesn't show up as a global in the Smalltalk >dictionary. The explain message says that it can't explain it. Yes, it does look puzzling. Here's the explanation: If you look closely, the Paragraph class uses a pool dictionary called TextConstants, which is defined and initialized (along with the CaretForm) in the Text class. At the time that Paragraph>>caretFormForDepth: was compiled, this dictionary existed, so the compiler found the value for CaretForm and placed it in the literal table for the CompiledMethod. Later, the TextConstants pool was accidentally removed before the final 1.3 image was saved. However, pre-existing CompiledMethods still held onto the literals used from that pool -- that explains why the method runs correctly, but you cannot re-compile it, explain CaretForm, etc. One of the early messages about 1.3 mentioned the accidental removal of the TextConstants pool -- to fix it, do: Text initialize. -- tim

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PWS ServerSocket Problem
by Matthew Rosen 03 Feb '98

03 Feb '98

Downloaded 1.30 and played with the delightful Pluggable Web Server stuff included. All seemed to work well. I took the image to the office and tried it on a machine there, and ran into trouble. After setting the ServerAction class methods appropriately and executing PWS initializeAll, I executed: [PWS serveOnPort: 8080 loggingTo: 'log.txt'] fork just as I had done earlier. Squeak went into an endless loop (no response to mouse clicks or Alt period, TaskManager showing 99% CPU utilization by Squeak). Debugging the serveOnPort: loggingTo: method, the problem seems to manifest in the bindTo: backLog: method of ServerSocket. Oddly, stepping into the code does not illuminate the cause of the endless loop, but instead crashes Squeak with the following stack dump: Mon Feb 02 10:45:04 1998 Current byte code: 0 Primitive index: 87 Stack dump follows: 17982908 [] in ServerSocket>bindTo:backlog: (i.e. there may be two problems here, one with sockets and one with debugging?) The same machine can successfully do things like display html source for a URL hyperlinked from a comment, for example. I tried downloading a fresh image and a different machine, with the same result! The machine where PWS works is on the same network, but dialed in via PPP instead of hardwired. Same OS (WinNT 4, SP3) on both. Tried the same installation procedure and test on a Mac, and it worked like a charm. Any suggestions? -- Matt Rosen San Joaquin Delta College

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Re: Smalltalk Design Question
by Mike Klein 03 Feb '98

03 Feb '98

> I wrote: > > > It certainly would be nice for the corrector to change > > > > iszero -> isZero > > > > but it would be nicer, still for it to correct: > > > > expandCollection -> growCollection > > > > or > > > > emitFourBytes -> emit4Bytes > > > > sort of a thesaures based corrector. > > Yeah, exactly what I wanted all those years: > > A Do-What-I-Mean-Not-What-I-Say approach to programming. > > The ideal thing would be a syntax checker and corrector which > would generate working programs even if I just rolled my head > on the keyboard. :-) Forget Do-What-I-Mean... press the Do-WantI-Want button. (It's labeled "on/off" or "0/1" on most computers) Trust me... It's really what you want. :-) > I'm not saying that those little helpful tricks such as spell > checking, automatic declaration of variables etc. are bad. > They're actually quite useful, and whenever I'm forced to use > VisualAge at a customer project I yearn for the helpfulness > of Smalltalk-80 derived system such as VisualWorks or Squeak. > Likewise, I'm sure. > > So please, if you think you have a great idea that would make > programming a breeze, just implement it in Squeak, and see whether > it really helps. It's not that difficult. But please stop the > endless discussion... I've found that it does help, mostly in a browsing context, though the system is not-ready-for-prime-time. (but then neither is Squeak). Please do not ask people to stop discussions that you personally find uninteresting. I don't like reading newbie questions, or bug fixes for systems I dont use, but that's why we have the 'delete' command. > nuf said Not enough for me... Also, remember, comments such as yours were also leavied against polymorphism. "I don't what the computer to guess what function I'm calling...I want to tell it explicitly" Cheers, Mike Klein

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Re: Transcendental Numbers
by Mike Klein 03 Feb '98

03 Feb '98

> True, there are non-commutative maths, but the ones that I can think of > offhand that are generalizations of the ones implemented in Squeak, such > as quaternions and Cayley numbers, are built out of components which are > manipulated by commutative operators. So it seems reasonable to build > the general number system such that the standard operators (addition and > multiplication in particular) are commutative, and then design the > non-commutative systems with the appropriate constraints, rather than > constraining the base number systems to favor the more complex and > less-used non-commutative systems. If you are attempting to do some kind of generic functions, you will have to deal with non-commutative math anyway, I.E. for subtraction and division. It only takes a little bit of care to preserve argument order for the traditionally-commutative operations of addition and multiplication as well, so it is better to preserve it when you can. I feel it IS worth the care for numerics. I.e. (s is a scaler, X is multiplication) | a b | | c d | X s = | as bs | | cs ds | and s X | a b | | c d | = | sa sb | | sc sd | Symbolic math can be a bit tougher: (x + y)(x + y) = x^2 + xy + yx + y^2 hence, you may want to be able to specify that the algebra is commutative to the reduction engine. -- Mike Klein

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Re: Documentation for Morphic framework
by ocit.inc 03 Feb '98

03 Feb '98

Where may I find docs that describe the intent of this framework. Thanks. Charles OCIT

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RE: Double-clickable app proposal
by Serg Koren 02 Feb '98

02 Feb '98

The Mac is easy to do...just put the image file in the resource fork as a data resource. Not sure about BeOS yet...should be do-able, but I'm still working on the port ;-) (Decided to redo the VM as a true OOP as opposed to trying to kludge it) S ----------------------------------------------------------------------------------------------------- Serg Koren Principal VisualNewt Software, Makers of Newt'sPaper(tm): http://www.VisualNewt.com/ ---------------------------------------------------------------------------------------------------- On Monday, February 02, 1998 4:38 PM, Andreas Raab [SMTP:raab@isgnw.cs.Uni-Magdeburg.DE] wrote: > > What if a Squeak VM file could recognize if an image file were simply > > appended to it, and do the right thing? Then it should take no more to > > make a double-clickable app than to do a save followed by a file copy. > > Sounds good! > > > OS gurus: Can this be done simply on the Mac PPC, 68K, Windows, Unix, > > OS/2, etc? > > I just tried appending stuff to an executable on Win95 and I could start > it. It's not fully clear how to find the image in the executable and I > also assume that a number of virus scanners will complain about undeclared > data in the executable, but in general it looks as if it works. > > Andreas > > -- > Linear algebra is your friend - Trigonometry is your enemy. > +===== Andreas Raab ============= (raab(a)isg.cs.uni-magdeburg.de) =====+ > I Department of Simulation and Graphics Phone: +49 391 671 8065 I > I University of Magdeburg, Germany Fax: +49 391 671 1164 I > +=============< http://isgwww.cs.uni-magdeburg.de/~raab >=============+ >

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Re: #gcd: bug
by Preston Briggs 02 Feb '98

02 Feb '98

>> Huh? In what sense is 0 generally null? In some countries, 0 (zero) is pronounced "null". That is null = 0 = zero ~= nil Preston

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Re: Window with buttons
by Tim Olson 02 Feb '98

02 Feb '98

>- is there any way to set the button's size so that it does not cover the >window's entire area? > >- how do you juxtapose several buttons in the same window? > >- how do you tell Squeak to give the buttons a border? > >(Basically, what I am trying to do is figure out how to create basic user >interface items in a window). > >Many thanks. Here's a little snippet that might help you see how to do these things. Also, you might want to look at Morphic, where you can do all this graphically. | topView textView text button | topView := StandardSystemView new backgroundColor: Color lightBlue; borderWidth: 2; label: 'Button Switchbox'; minimumSize: (300@200); maximumSize: (300@200). text := 'Hello, World!' asDisplayText. textView := DisplayTextView new model: text; window: (0@0 extent: 40@8); borderWidth: 2. 0 to: 15 do: [:i | button := SwitchView new model: Switch new; label: (i printString asParagraph); borderWidth: 2; window: (0@0 extent: 8@4); foregroundColor: Color red; backgroundColor: Color yellow. topView addSubView: button align: button viewport topLeft with: ((i \\ 4) * 10) @ ((i // 4)+1 * 10)]. topView addSubView: textView. topView controller open. -- tim

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