Squeak-dev November 1999

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164 participants
545 discussions

Polymorphism and language
by Adam Bridge 02 Aug '00

02 Aug '00

I wonder if we're not asking the wrong question here. Language, it seems to me, is for expression. If we design a language (as opposed to allowing it to evolve) then we should have a goal for that language. What's the goal here? Although polymorphism is certainly an interesting capability shouldn't we be looking at the kinds of tasks we wish to perform? Would we demand an artist work in tempra when water color is what expresses the mood best? Personally I like the idea of small languages that do some things very very well. They are easy to learn because their concepts are clear. If languages can agree on ways to intermingle so I can write my image manipulation in one language and my text in another and my GUI in yet another -- and have them work together intimately and EASILY -- then I think we have a software system which is about expression first and language second. I'd love to easily, trivially, combine Smalltalk, Perl, Fortran, Obj-C and be able to easily explore other languages in this same context: it becomes easy to grow. Adam Bridge

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unsubscribe
by Alek 09 Jun '00

09 Jun '00

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[ENH] FreeCell-changes.7.cs
by Pennell, David 10 Dec '99

10 Dec '99

------_=_NextPart_000_01BF249B.04E2A4DA Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01BF249B.04E2A4DA" ------_=_NextPart_001_01BF249B.04E2A4DA Content-Type: text/plain; charset="iso-8859-1" Bug fixes and enhancements for FreeCell 1) Fix typo's in Help. 2) Disallow stacking on the free cell's 3) Pause timer if in a SystemWindow and put to sleep (collapse or another SystemWindow becomes active) 4) Don't include auto play time if it results in game being won. -david ------_=_NextPart_001_01BF249B.04E2A4DA Content-Type: text/html; charset="iso-8859-1" <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1"> <META content="MSHTML 5.00.2314.1000" name=GENERATOR></HEAD> <BODY> <DIV><FONT face=Arial size=2><SPAN class=053394618-01111999>Bug fixes and enhancements for FreeCell</SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=053394618-01111999></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=053394618-01111999>1) Fix typo's in Help.</SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=053394618-01111999>2) Disallow stacking on the free cell's</SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=053394618-01111999>3) Pause timer if in a SystemWindow and put to sleep (collapse or another SystemWindow becomes active)</SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=053394618-01111999>4) Don't include auto play time if it results in game being won.</SPAN></FONT></DIV> <DIV><FONT face=Arial size=2><SPAN class=053394618-01111999></SPAN></FONT> </DIV> <DIV><FONT face=Arial size=2><SPAN class=053394618-01111999>-david</SPAN></FONT></DIV></BODY></HTML> ------_=_NextPart_001_01BF249B.04E2A4DA-- ------_=_NextPart_000_01BF249B.04E2A4DA Content-Type: text/plain; name="FreeCell-changes.1.cs" ; x-mac-type="65417070" ; x-mac-creator="43534F6D" Content-Disposition: attachment; filename="FreeCell-changes.1.cs" Content-Transfer-Encoding: imap_stub 0,735,2,7574,0, ------_=_NextPart_000_01BF249B.04E2A4DA--

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[enh] Form>>writeGIFFileNamed:
by Mark Guzdial 06 Dec '99

06 Dec '99

There is a writeBMPFileNamed: in Form, but I often want snapshots in GIF format. So I wrote a short bon mots to provide similar functionality for GIF. (I keep (Form fromUser) writeGIFfileNamed: 'snapshot.gif' in my Do menu.) Finding myself filing it in for the umpteenth time, I thought someone else might find it useful. 'From Squeak 2.5 of August 6, 1999 on 20 September 1999 at 12:05:48 pm'! !Form methodsFor: 'fileIn/Out' stamp: 'mjg 9/20/1999 12:05'! writeGIFfileNamed: aFile GIFReadWriter putForm: self onFileNamed: aFile. ! ! -------------------------- 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: Some questions about Squeak
by Stephane Ducasse 01 Dec '99

01 Dec '99

Thanks So what is the relationship between World and Display then? For the morphic turtle I know but I would like to have something working for friday and I can only work on it before bedtime ;)

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RE: Intervals
by Jarvis, Robert P. 01 Dec '99

01 Dec '99

> -----Original Message----- > From: Peter Crowther [SMTP:Peter.Crowther@IT-IQ.com] > Sent: Tuesday, November 30, 1999 9:25 AM > To: 'squeak(a)cs.uiuc.edu' > Subject: RE: Intervals > > You're still assuming steps at, or of the order of, 1. > <sigh> Guilty as charged. I also confess to having missed an edge condition. Dare I hope for a velvet rope with which to be hung, m'lud? :-) 'From Squeak2.6 of 11 October 1999 [latest update: #1559] on 30 November 1999 at 11:07:18 am'! !Interval methodsFor: 'accessing' stamp: 'rpj 11/30/1999 11:04'! includes: aNumber "Determine if aNumber is an element of this interval." ^(self rangeIncludes: aNumber) and: [ self valuesInclude: aNumber ]! ! !Interval methodsFor: 'private' stamp: 'rpj 11/30/1999 11:01'! rangeIncludes: aNumber "Private" ^aNumber between: (self first min: self last) and: (self first max: self last)! ! !Interval methodsFor: 'private' stamp: 'rpj 11/30/1999 11:04'! valuesInclude: aNumber "Private - answer whether or not aNumber is one of the enumerated values in this interval." ^(aNumber - self first \\ step = 0) or: [ ((aNumber - self first \\ step - step) abs < (step * 1e-10) abs) or: [ (aNumber - self first \\ step) abs < (step * 1e-10) abs ] ]! ! I know the addition of a fudge factor may cause problems in some cases, but it does (help) Squeak support Dan's Principle of Least Astonishment. To me it's quite amazing that Squeak says (1.0 to: 20.0 by: 0.2) includes: 1.2 ==> false while it's (a bit) less amazing for it to say (1.0 to: 20.0 by: 0.2) includes: 19.999999999999 ==> true Of course, all this mucking about with Floats is going to come back to haunt us at some later date. Floats, as I think I've mentioned in the past, are evil... Bob Jarvis Compuware @ Timken

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MVC Cookbook as PDF
by Stephen Travis Pope 01 Dec '99

01 Dec '99

I know it's a little bit embarassing to be asking about your own paper on-line, but I seem to recall that someone had scanned the old JOOP by Glenn Krasner and me about MVC -- does anyone know if/where this is available? -- stp Stephen Travis Pope -- http://www.create.ucsb.edu/~stp stp(a)expertcity.com -- stp9(a)cornell.edu

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Primitive: returning a String
by Giovanni Giorgi 30 Nov '99

30 Nov '99

Excuse me, I am working with named-primitive and I need to return a char* (= a String) to Smalltalk. The String is not of fixed or known size when calling the primitive. I have searched in the documentation but I cannot find how to solve this problem. I must return an array of integer and then conver it? What is the best way to do this? Thank you very very much! -- // Giovanni Giorgi mailto:giovanni.giorgi@mlab.disco.unimib.it // Master Thesis at http://mars.sal.disco.unimi.it/~giorgi // Student (& exTutor) at Depart. of Computer Science of Milan, Italy. -------------------------------------------------------------------------

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MPW VM Support in 2.7?
by Stephen Travis Pope 30 Nov '99

30 Nov '99

Hello all, Is anyone else using MPW to compile Mac VMs (as per Andrew Greenberg's Sept. 5th changeSet)? It actually works as advertised and is measurably faster. I can post the updates to the 2.6 VM to make this work if there's anyone interested. What would it take to get Andrew's #ifdefs included in the VM support sources in 2.7? On a related note: Is anyone working on a modular (i.e., smaller pieces) interp.c? -- stp Stephen Travis Pope -- http://www.create.ucsb.edu/~stp stp(a)expertcity.com -- stp9(a)cornell.edu

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Re: Shouldn't 2 hash = 2.0 hash? [LONG]
by R. A. Harmon 30 Nov '99

30 Nov '99

At 04:26 PM 11/29/99 -0500, David N. Smith wrote: >At 17:33 -0600 11/28/99, R. A. Harmon wrote: >>I found the following: >> >> 2 = 2.0 -> true >> 2 hash = 2.0 hash ->false >> >>I think this is a bug. Is it? > >Good question. The blue book says: [snip] >(I cannot find any reference in the blue book to another hashing >rule: The hash value of an object must be constant over time. There The ANSI doc in <Object> hash says: "The hash value of an object need not be temporally invariant. Two independent invocations of #hash with the same receiver may not always yield the same results. Note that collections that use #= to discriminate." >So, by the Blue Book definition, what you observe is a bug. [snip] >Should it be? Does it really mean that two instances of wildly >differing classes must answer equal hashes when they compare equal? [snip] >All of the discussion in the Blue Book about hashing is in the >context of looking up values in a hashed collection. Did they intend >that someone might put a float 2.0 into a hashed collection and then >look it up with an integer 2? Do people do it? I was also concerned with the ANSI definition as I'm trying to produce all the ANSI conforming messages for Squeak, and that I thought there may be an unpleasant surprise in collections you mentioned. I would think there are good reason way folks might do it. >Maybe there is some other reason for this rule, but I think it might >just be incompletely stated. Consider these cases: [snip] >So, maybe the rule should state something about closely related >objects answering the same hash, but I don't see a good and simple >way to say it. I like the ANSI standard way as it relieves me of having to be creative, and I get to rely on the committee's greater experience. I also wondered if there was a specific reason Squeak does it this way, and I thought I'd leverage off this list's greater experience. >Are subclasses of Number closely related enough that they should >follow the rule? >Most Smalltalk systems do what you expect. Squeak Dolphin VWNC 2 = 2.0 true true true 2 hash = 2.0 hash false true true How about VAST? [Good analysis snip] >There are similar problems with scaled decimal values. I can't recall how I handled this in my Scaled Decimal implementation for Squeak. Squeak Dolphin VWNC 2 = 2.0s2 ? true true 2 hash = 2.0s2 hash ? false true 2.0 = 2.0s2 ? true true 2.0 hash = 2.0s2 hash ? false true This may not be Dophin's fault as I contributed my Scaled Decimal implementation that they then modified (I haven't yet checked how much changed). It may be that my error may have slipped by them. How about VAST? >So, should the rule be followed even if it's more expensive to do so? [snip] >In my view, and assuming I'm not missing something obvious, the answer is no. > >I'd argue that having (2.0 = 2) answer false is better than forcing >the hashes to be equal. Besides, comparing floats is a sin one should >not encourage. I'd rather see #= answer false and that some other >method be used for 'has equivalent value'. That is the wisdom I've always heard, and my first impulse was that (2.0 = 2) should answer false. As a general rule, I use the ANSI standard messages and where it doesn't specify, I defer to other dialects where they agree, otherwise I have to think (not a happy occurrence). I use my general rule where possible so my programs are at least nominally portable. After checking on what Dolphin and VWNC does, I would vote for (2.0 = 2) answer true and (2 hash = 2.0 hash) answer true in Squeak. I haven't dug into how this is achieved At 05:41 PM 11/29/99 -0500, agree(a)carltonfields.com wrote: >This is an excellent discussion. It suggests to me that the blue book > notion of "="/hash and "==" do not properly contemplate the more general > notion of equality used in computing 2 = 2.0 under the present system. > The latter computation is much more than the notion of "represents the > same number," which is the Smalltalk/Blue Book notion of "=," but rather > is the more general notion of "after coercing both arguments to the same >level of generality in a specified hierarchy, represents the same number." [Good analysis snip] The ANSI doc in <Object> = says: "The meaning of "equivalent" cannot be precisely defined but the intent is that two objects are considered equivalent if they can be used interchangeably. Conforming protocols may choose to more precisely define the meaning of "equivalent". The value of (receiver = comparand) is true if and only if the value of (comparand = receiver) would also be true. If the value of (receiver = comparand) is true then the receiver and comparand must have equivalent hash values. Or more formally: receiver = comparand => receiver hash = comparand hash The equivalence of objects need not be temporally invariant. Two independent invocations of #= with the same receiver and operand objects may not always yield the same results. Note that a collection that uses #= to discriminate objects may only reliably store objects whose hash values do not change while the objects are contained in the collection." I find this a bit more slippery than I can get my mind around. First I think 2 and 2.0 are interchangeable and then I think they are not. Arrrrrrgh! Thanks to all others for good points. -- Richard A. Harmon "The only good zombie is a dead zombie" harmonra(a)webname.com E. G. McCarthy Spencer, Iowa

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