Squeak-dev April 1998

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107 participants
279 discussions

sqAPIs for Win32 & Mac available
by Alejandro F. Reimondo 26 Apr '98

26 Apr '98

I've released the 1.0 version for sqAPIs [Squeak API calls]. Currently under Win32 & Mac. (we are working to port to other OS). It can be downloaded from SUGAR's WEB site. http://www.sugarWeb.com/Miniatures/downloads.html [thanks to Jim Benson for the Mac implementation!] Ale. --------------------------------- Esta disponible la version 1.0 de soporte de API calls para Squeak. Actualmente soporta Win32 y Mac; aunque estamos trabajando para portarlo a otras plataformas. Pueden bajarsela desde SUGAR en http://www.sugarWeb.com/Miniatures/downloads.html [Gracias a Jim Benson por la implementacion para Mac!] Ale. --------------------------------- Alejandro F. Reimondo Feel free to visit Smalltalk User Group of Argentina (SUGAR) at http://www.sugarWeb.com

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Re: Bug in Rectangle>>containsPoint:?
by Tim Olson 26 Apr '98

26 Apr '98

Hi, Chris: >I seem to have found a bug in Rectangle. In the method > >containsPoint: aPoint > "Answer whether aPoint is within the receiver." > ^origin <= aPoint and: [aPoint < corner] > ^^^ > >the second comparison is a "<". I think it should be a "<=" instead. I think the definition as it exists is correct (or at least internally correct and consistent as used in Squeak). It's not explicitly stated anywhere, but a Rectangle consists of the set of points bounded by its origin and its corner, up to but not including the points on the corner's edges (right and bottom edges). This is because rectangles are frequently tiled, and if the exclusion didn't exist, there would be certain points that would be members of ajoining Rectangles, instead of belonging solely to one or the other. However, exclusion is fundamental to things like mouse hit detection, view layout, etc. Think of it this way: if you are told to paint a rectangle on a tiled floor, starting in the corner (corner: 0@0) and going for one tile's length in both directions (extent: 1@1), you would end up with a single tile painted, and would respond "no" to the question of whether the tile at 1@1 was painted. -- tim

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Re: Bug in Rectangle>>containsPoint:?
by Alan C. Kay 26 Apr '98

26 Apr '98

Tim -- Well, it was Dan's cells that came up with bitBLT! Cheers, Alan ------ At 4:25 PM -0500 4/25/98, Tim Olson wrote: >Alan wrote: > >>You are right again. I'll have to retrain those 70s brain-cells. > >Hey, if those are the same cells that came up with Smalltalk to begin >with, I'd keep 'em just the way they are... ;-) > > > > -- tim

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Re: HELP! formalizing OO
by Leandro Caniglia 25 Apr '98

25 Apr '98

Alan wrote: " However, as a card carrying mathematician, I don't believe that the trappings of classical math -- set theory, etc. -- will help. " On the other hand, my own experience has showed me that Squeak helps a lot to understand classical math ideas. Saludos, Leandro

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SmallInteger comment not correct
by Aik-Siong Koh 25 Apr '98

25 Apr '98

Instead of being 16 bits long as stated in their comment, SmallIntegers are actually 31 bits long. Aik-Siong Koh

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Re: Bug in Rectangle>>containsPoint:?
by Tim Olson 25 Apr '98

25 Apr '98

>I think you are right. You know, when Bill Atkinson did QuickDraw for the >Mac, he came up with a useful insight: to have the coordinates be zero >width and be located between the pixels, instead of being on the pixels. >This has many felicitous properties and perhaps someday we should convert >over to this convention for Squeak .... I think Squeak already works this way, at least under the Macintosh. Try: Display fill: (Rectangle origin: 1@1 corner: 2@2) fillColor: Color red. which plots a single red pixel on my Mac. Does it do something different (e.g. plot a 2x2 square of pixels) on other systems? I would suspect that it doesn't, otherwise some of the UI (borders, etc.) might look strange. If all systems plot the single pixel, then the various VMs must be handling the interface to the underlying display such that they are all treating it as a "zero width coordinate, between pixels" organization. -- tim

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Re: Squeak support for AIX
by Reinier van Loon 25 Apr '98

25 Apr '98

Hola Ale, > Is Squeak ported to AIX platform? I've ported the Squeak to AIX (see my home page). > Where can I download the VM sources? You can use the normal UNIX sources but you cannot use the make file (at least I couldn't). See my Squeak Download Area for more details. Saludos, Reinier.

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Squeak support for AIX
by Alejandro F. Reimondo 25 Apr '98

25 Apr '98

Is Squeak ported to AIX platform? Where can I download the VM sources? Ale.

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the case for two's complement
by Ian Piumarta 25 Apr '98

25 Apr '98

I thought some of you might enjoy this. (I think at least Eliot probably will. ;) Ian -------- Beeler M., Gosper, R.W. and Schroeppel, R., "HAKMEM", MIT AI Memo 239, Feb. 29, 1972. ITEM 154 (Gosper): The myth that any given programming language is machine independent is easily exploded by computing the sum of powers of 2. - If the result loops with period = 1 with sign +, you are on a sign-magnitude machine. - If the result loops with period = 1 at -1, you are on a twos-complement machine. - If the result loops with period > 1, including the beginning, you are on a ones-complement machine. - If the result loops with period > 1, not including the beginning, your machine isn't binary -- the pattern should tell you the base. - If you run out of memory, you are on a string or Bignum system. - If arithmetic overflow is a fatal error, some fascist pig with a read-only mind is trying to enforce machine independence. But the very ability to trap overflow is machine dependent. By this strategy, consider the universe, or, more precisely, algebra: let X = the sum of many powers of two = ...111111 now add X to itself; X + X = ...111110 thus, 2X = X - 1 so X = -1 therefore algebra is run on a machine (the universe) which is twos-complement.

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Bug in Rectangle>>containsPoint:?
by Chris Reuter 25 Apr '98

25 Apr '98

Hi all, I seem to have found a bug in Rectangle. In the method containsPoint: aPoint "Answer whether aPoint is within the receiver." ^origin <= aPoint and: [aPoint < corner] ^^^ the second comparison is a "<". I think it should be a "<=" instead. (Yes, I know this is nit-picky, but I'm writing code affected by this particular behavior and I'd like to know whether it should be changed or not.) --Chris

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