Squeak-dev January 1998

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81 participants
196 discussions

Fix for String>withBlanksTrimmed in 1.3
by Georg Gollmann 30 Jan '98

30 Jan '98

String>withBlanksTrimmed breaks on empty strings in Squeak 1.3, here is a fix: !String methodsFor: 'converting' stamp: 'go 1/29/98 13:25'! withBlanksTrimmed "Return a copy of the receiver from which leading and trailing blanks have been trimmed. Simplified by Gerardo Richarte 11/3/97. Fixed for empty strings by go 1/29/98 13:24" self size = 0 ifTrue: [ ^self ]. ^ self copyFrom: (self findFirst: [:eachChar | eachChar isSeparator not]) to: (self findLast: [:eachChar | eachChar isSeparator not]) " ' abc d ' withBlanksTrimmed"! ! Georg ---- Dipl.Ing. Georg Gollmann TU-Wien, EDV-Zentrum phon:(+43-1) 58801 - 5848 fax: (+43-1) 587 42 11 mail:gollmann@edvz.tuwien.ac.at http://macos.tuwien.ac.at/Gollmann.html

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More beginner's questions
by Philippe de Rochambeau 30 Jan '98

30 Jan '98

I am reading through Wilf Lalonde's "Discovering Smalltalk" and attempting to run the following code in Squeak: | aPen | aPen := Display pen. aPen place 100@100. aPen goto: 200@100. aPen goto: 200@200. etc. What is the equivalent of the "aPen := Display pen." line in Squeak? Furthermore, what is the equivalent of "Prompter prompt: "Your name?" default: 'Wilf'" in Squeak? Many thanks. Philippe de Rochambeau

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stdin and stdout in Squeak
by Kohler Markus 30 Jan '98

30 Jan '98

Hi, Is there any way for a headless Squeak image to read from stdin and print something to stdout ? Thanks, Markus -- +----------------------------------------------------------------------------+ | Markus Kohler Hewlett-Packard GmbH | | Software Engineer OpenView Software Division | | IT/E Response Team | +----------------------------------------------------------------------------+

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Three beginner's questions
by Philippe de Rochambeau 30 Jan '98

30 Jan '98

1) What is the easiest way to draw a graphical object (e.g., a line)? Can you draw in the Workspace or must you draw on a special canvas? Could you provide a simple example? 2) How do you include a character such as a single quote in a Squeak string; i.e., what is the equivalent in Squeak SmallTalk of "\'" (I am aware of the fact that you can always replace the single quote by a double quote as in 'John"s', but I wonder if there is another solution)? 3) What is the easiest way to generate a simple window containing a button, in Squeak? Any answers to these questions would be much appreciated. Philippe de Rochambeau

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Re: multithreading support
by Les Tyrrell 29 Jan '98

29 Jan '98

This might also be of interest: http://web.yl.is.s.u-tokyo.ac.jp/members/jeff/research/coda.html

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Re: Case-insensitive selectors
by Travis Griggs 29 Jan '98

29 Jan '98

---------- From: Dan Ingalls <DanI(a)wdi.disney.com> To: squeak(a)cs.uiuc.edu Subject: Re: Case-insensitive selectors Date: Thursday, January 29, 1998 8:53 AM <snip> > 3. One step which would help with the real problem, without any significant > compatibility issues, would be to recognize and discourage the definition of a method > whose pattern is equal to an existing pattern in letters but not in case. This seems like it might be an interesting thing to add the RefactoringBrowser's suite of "warnings". Is any work being done to port RB to Squeak? I know the idea's been kicked around, but have heard that anyone is actually doing it. -- Travis Griggs Key Technology tgriggs(a)keyww.com GO SMALLTALK - AND BEYOND!

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Re: multithreading support
by Les Tyrrell 29 Jan '98

29 Jan '98

> Could you please provide an ISBN or publisher for that? The Design and Implementation of Concurrent Smalltalk Yasuhiko Yokote Keio University Japan ISBN 981-02-0112-5

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Re: Case-insensitive selectors
by David N. Smith 29 Jan '98

29 Jan '98

At 11:53 -0500 1/29/98, Dan Ingalls wrote: > >3. One step which would help with the real problem, without any >significant compatibility issues, would be to recognize and discourage the >definition of a method whose pattern is equal to an existing pattern in >letters but not in case. I like this, and it sounds like 3 lines of code in the right place in the compiler. It's very similar to the current feature which complains when there is NO method which matches (which should take care of isUpperCase versus isUppercase kinds of situations already). However, I've never had much problem with spelling methods with difference character cases and not immediately finding the misspellings, and IMHO I don't think it's worth much effort to fix. Dave _______________________________ David N. Smith IBM T J Watson Research Center Hawthorne, NY _______________________________ Any opinions or recommendations herein are those of the author and not of his employer.

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Re: Smalltalk Design Question
by Ranjan Bagchi 29 Jan '98

29 Jan '98

That'd be cool. Implementation, I guess, would be through some kind of collection of semantic rules which tranform what you type into what it thinks should be there (realizing that '4' is equivalent to 'Four' is equivalent to 'four', blah blah blah). My only question regarding actually doing this would be of efficiency -- I remember seeing at one of the PPD developer conferences a package which would make the editing view in the browser automatically color and format the code -- as it was typed in. Sort of like what Visual C++ does. In fact, nearly exactly, because it used a DLL and external calls -- the person who wrote it said that the smalltalk implementation ran too slowly. 'Couse that was back when a p133 desktop was top of the line and would set you back 4000. Go Moore, Go. -rj -----Original Message----- From: Mike Klein <mike(a)twinsun.com> To: squeak(a)cs.uiuc.edu <squeak(a)cs.uiuc.edu> Date: Thursday, January 29, 1998 1:08 PM Subject: RE: Smalltalk Design Question >Someone earlier (Vassilli, I think) metioned that the case problem is more >of an issue with the corrector, and that method lookup was actually based >on the identity of the selectors. > >Some ideas: > >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. > >-- Just rambling, >Mike Klein >

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Re: Transcendental Numbers
by Mike Klein 29 Jan '98

29 Jan '98

> I think we're seeing this through a bit different eyes. It is not clear to > me whether your mixed math with Polynomials was commutative. IOW, that not > only could you perform: > > polynomial + 4 > > but also that you could perform: > > 4 + polynomial > > IMO, any mixed math you add to the system, should be communtative. VS, IMO, > did not do a complete implementation of the DD stuff. At least as far as > points goes. In 3.0.1, you could add a simple number to a point, but not a > point to a number. I would argue in VS, that you hadn't done DD (not the > way I understand it). To have implemented it the way I understood it, you > would've done something like: > > Polynomial>>+ aNumber > ^aNumber sumFromPolynomial > > Then, for any potential argument you would've implemented the > sumFromPolynomial: message, *including in Polynomial itself*. That's the > beauty of DD, is that there are NO isThisOrThat checks and subsequent > branches. The traversal of messages ends up in the right place. Personally, I think that Double Dispatching (DD) is a better way to go than coersions. VW implements both, using coersion to avoid the n^2 problem with DD. The problem with coersion, is that it implicitly assumes a tower of types, that is to say, a tree where each node has only one child. Thus, it is "trivial" how to raise or lower a numeric type. The problem is, this simplistic scheme only works for the simplest of arithmetic embedings, i.e. Rational->Integer. Even adding the "Real" type to the tower raises all sorts of thorny problems which are usually ignored by the Real == FloatingPoint camp. There is a rather good discussion of the issues in Structure and Interpretation of Computer Programs (using Scheme as a language). If you want to see how easy it is to make mistakes in this area, and have access to VW: notice that: (3@4) * (5 + 6i) evaluates to: 15@24 (3+ 4i) * (5 + 6i) evaluates to: (-9 + 38 i) ______ ((1/3) raisedTo: 0) isInteger evaluates to: false 123456781234567812345678i real isZero evaluates to: false ______ The moral of the story is that unification must proceed very carefully lest the unity you acheive be only valid in a limited context. For instance, is (x^2 + x + 2) the same polynomial as (y^2 + y + 2) ? The answer is yes, if they are considered as functions, but no if they are considered as syntactical forms. Is the real number 4 the same as the complex number (4,0) ? There is a natural isomorphism between complex numbers with a zero real part, and the real numbers, and, most fortunately, this embedding preserves most of the laws of real arithmetic when extended (or mapped) into the complex domain. A similar embedding puts the natural numbers into the integers into the rationals into the algebraics. However, the "natural" isomorphism between Smalltalk Points, and complex numbers is not so natural, as my example above shows. I have been playing around with this stuff for a while, and I've found that coersion is, in general, a bigger problem than it is worth. It only works properly when the number of types is small. But when the number of types is small, the n^2 DD issue, just isn't tooooo difficult to swallow. -- Mike Klein

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