Squeak-dev September 2001

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168 participants
408 discussions

Re: Storing and Retrieving Point
by raymondasselin＠sympatico.ca 29 Sep '01

29 Sep '01

"Richard A. O'Keefe" <ok(a)atlas.otago.ac.nz> wrote: > raymondasselin(a)sympatico.ca wrote: > > >pt _ Point new. > > >pt _ 25@125. > > -There is lots of examples in Smalltalk which suggest something like > Morph new, or Foo new, so for me this was not linked to the use of > declaring the type of a variable. > -I know that when you try to define new for a Class you defined, Squeak > answer a caution 'new is used in the existing class system......' I > usually ignore it and go forward. > > Your remark is intriguing to me...did this means that it's not a good > way to go to define a 'new' as a 'builder' Class method in Squeak ? > I'm a little bit 'confus' because before your note I was pretty sure > that pt_ Point new. was the way to go !!! > > John's point was that in > "1" pt _ Point new. > "2" pt _ 25@125. > the first step is superfluous. In optimising compiler terms, the value > it constructs is "dead", it can never be used. The code that creates a > new Point has no side effects, so it doesn't accomplish anything useful > to create a new point and then throw it away. The second step does not > modify the Point created in line "1", it constructs a whole new Point & > just rebinds the variable pt. > > #new is indeed the usual selector for creating new objects. > It's not the only one. In this case, > > "3" pt _ Point x: 25 y: 125. > > would have had the same effect as step "2". > > There is actually a problem with using Point new. We normally think of > a Point as an object having some kind of number for an x coordinate and > some kind of number for a y coordinate (and possibly other stuff it is > belongs to a subclass of Point), but > "1" pt _ Point new > returns a new point such that pt x is nil and pt y is nil. Another way > to come up with a suitable point would be > > "4" pt _ Point new x: 25; y: 125. > or > "1'" pt _ Point new. > "2'" pt x: 25; y: 125. Hi Richard thank for your reply. The point for me is now so clear that I'm feeling stupid to didn't perceive it sooner. 25@125 create a point, it is not only an assignation of values to x and y part of a point. Raymond

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Re: Storing and Retrieving Point
by raymondasselin＠sympatico.ca 29 Sep '01

29 Sep '01

Bob Arning <arning(a)charm.net> wrote: > Ken, > > The literal array syntax "#()" only handles literals - symbols, strings, numbers, characters. Thus it interprets pt as #pt. Either > > dict at: 'first' put: {'text'. pt}. > > or > > dict at: 'first' put: (Array with: 'text' with: pt). > > will do what you want. > > Cheers, > Bob > > > On Thu, 27 Sep 2001 14:08:53 -0600 "Ken G. Brown" <kbrown(a)tnc.com> wrote: > >I'm having trouble storing and retrieving Points. What am I doing wrong? > > > >pt _ Point new. > >pt _ 25@125. > >dict _ Dictionary new. > >dict at: 'first' put: #('text' pt). > >readPt _ ((dict at: 'first') at: 2). "readPt is now a Symbol" Hi Bob can you explain a little bit the construct {'text'. pt} what is the semantic of these accolades '{ }' I did'nt find them in the Smalltalk books I get. What they means and for which uses were they made? Same for the meaning of the '.' between 'text' and pt. Raymond

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Re: Storing and Retrieving Point
by raymondasselin＠sympatico.ca 29 Sep '01

29 Sep '01

Martin McClure <martin(a)hand2mouse.com> wrote: > At 9:18 PM -0400 9/27/01, raymondasselin(a)sympatico.ca wrote: > > [...] > > > > > >> Therefore all you really need to do is > >> pt _ 25@125 > >> > >snip.... > > > >John > >What you say is new to me > > > >-There is lots of examples in Smalltalk which suggest something like > >Morph new, or Foo new, so for me this was not linked to the use of > >declaring the type of a variable. > >-I know that when you try to define new for a Class you defined, Squeak > >answer a caution 'new is used in the existing class system......' I > >usually ignore it and go forward. > > > >Your remark is intriguing to me...did this means that it's not a good > >way to go to define a 'new' as a 'builder' Class method in Squeak ? > >I'm a little bit 'confus' because before your note I was pretty sure > >that pt_ Point new. was the way to go !!! > > Sending a class the message new is indeed the most common way of > creating a new instance in Smalltalk. However, in this particular > case it was not needed, because many classes define other methods > that create instances, and Point is one of them. In fact Point is one > of the minority of classes where #new is not even a useful way to > create instances. > > Let's take a look at the original code example: > > pt _ Point new. > pt _ 25@125. > > The first statement sends the message #new to the class Point, which > creates a new Point and answers it. The variable pt is now assigned a > reference to this new point, whose x and y instance variables are > each nil. ...each nil... this is so evident that I didn't saw it before. With pt _ Point new. I get an empty point.... so this is like 'declaring the type of a variable' as John M McIntosh said in a previous message. > The second statement sends the message #@ to the literal Number 25 > with the single argument a literal Number 125. Numbers respond to the > #@ message by creating and answering a new Point with the receiver as > the x coordinate and the argument as the y coordinate. > > So the second statement creates a second instance of Point, this one > with reasonable values for x and y, and assigns to pt a reference to > this second Point. The first, unitialized, Point is now not > referenced and will be garbage collected. > So, except for eating a little more processor time, the second > statement alone has exactly the same effect as both statements. OK this is really clear now. > Is there a way to do this that uses the more familiar pattern of > creating an unitialized instance and then initializing it? Yes, but > in this case it's bad form. I'll explain. You could write: > > pt _ Point new. > pt setX: 25 setY: 125. That's it... I missed the fact that #@ is an instance creation message, partly because two numbers and the arrow _ conducted me to assimilate the right part of the expression (25@125) with an assignation of values to the point created the line before. Or as you explained this is'nt an assignation of values but a reference to a new instance of point. > which creates an unitialized Point and then sends that Point a > message that initializes it. However, this is NOT good form, since > the method Point>>setX:setY is in Point's 'private' category. Points > are intended to be immutable, with each instance getting its x and y > values at the time it's created and never changing them again. By the way, it would be very interesting if Squeak could clearly separate public method of privates one differently than by just putting them in a category! > If in doubt about what message to send a particular class to make a > new instance, browse the class-side methods of that class and its > superclasses, by convention under the category 'instance creation'. > > > Hope this helps, > > -Martin Thank you Martin for these explanations.

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[ANN] Squeak RB release
by danielv＠netvision.net.il 29 Sep '01

29 Sep '01

Hey guys, another release is up. A couple of fixes, and one main new feature - a search feature based on parse tree matching. This lets you find just about any pattern in the code that you can describe. You can look in a class, a class category, or all the system (that'll take a while!). The way the search work is like this - You give it a pattern that looks like the code you want to match `@exp halt will match "3 halt" and also "(3 + 4) halt". You can also specify a test clause. For example, The pattern - `@Expression with the test clause - aNode isVariable and: [(class _ Smalltalk classNamed: aNode name) isBehavior and: [class allSuperclasses includes: Morph]] Will look for every expression, that's a variable, that's really a global, and a class, and a subclass of Morph (In short, you'll see all the methods that reference some Morph class explicitly). Note that the clause is really compiled as the body of a block, that recieves aNode as it's only parameters. To invoke the search, go to the "RB - Class" menu, and poke the "ind code like..." item. Invoking it with no class will apply the search to the category, if no category either, then all categories. To load the RB, do (btw, tests show you must delete any Squeak%20RB projects from your Squeaklets directory) - ProjectLoading installRemoteNamed: 'Squeak%20RB.pr' from: 'http://squeak.heeg.de:8080/TFODC69UQ0MFRIHMG40DRML1CU7VYZ9-4/Squeak%20R B.pr' named: 'SqueakRB' in: Project current. Daniel PS - anyone know the rationale for Project>>fromUrl: working only for the predefined servers?

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Re: Storing and Retrieving Point
by raymondasselin＠sympatico.ca 29 Sep '01

29 Sep '01

John M McIntosh <johnmci(a)smalltalkconsulting.com> wrote: > > Ok, well this can be a complicated subject. When you create an > instance you face the issue of instance creation and how the designer > of the class wants you to do it. If he has a "complete instance > creation method", usually found in the class instance creation > category, then you can use that. > That, I understand! > Doing a new on the class then poking at the instance might also work, > but then again it might not correct. > > For a simple example > > thing _ OrderedCollection with: #foo > > versus > thing _ OrderedCollection new. > thing add: #foo. > > Both achieve the same results, but as you see they are different. Yes, this is two ways of doing the same thing... > A more complex example might be > thing _ ComplicatedDataBaseConnector useHost: 'database.apple.com' > > If you invoke new against ComplicatedDataBaseConnector it might not > do everything you need and you need to invoke other methods against > the instance that require more knowledge to arrive at the same state. Yes, I usually do ComplicatedDataBaseConnector new initialize. and put everything that must be done in the instance method 'initialize'. As I see it your ComplicatedDataBaseConnector useHost: 'database.apple.com' is a specialized constructor > Also if someone wants to change how the instance creation method > useHost: worked, then you could be impacted if you had new and > various other methods to achieve the same state. Some classes for > example forbid the use of new because of this issue. OK... so my 'Foo new initialize' is too general in the sense that this doesn't really tell the programmer what is going on, and if I have to change something the chances are that I will have to make changes to a lot of places. > > new and overriding new. > > You get the warning because you are messing with an issue. Typically > you add a new method to your class to do ^super new initialize > > This is to allow the inherited class the ability to run new, then you > run your initialization to set anything up that is required. Go take > a look at OrderedCollection new: versus new. > > new does > ^self new: 10 > > new: anInteger does > ^ super new setCollection: (Array new: anInteger) > > > In this case as you see new actually invokes new: which then invokes > super new and pokes at itself to set instance variables. One could > have had an instance side initalization method aka ^super new > initialize: anInteger. to do this instead, but 20 years back it was > written the way it was. Ok I'm on the road again. > basicNew > I seem to recall various folks have written lots of papers on this so > I'm not going to attempt much discussion here, but some people feel > that at some point in a root class you need to invoke ^super basicNew > initialize. to reduce redundant initialization of instance variables. > Also there are other reasons for invoking basicNew. > > > But back to your question about Point new the correct way, if not for > the fact we get an instance of Point by using the @ (technically it's > a binary operator @ against a instance of Number which invokes > primitive 18) you could either do > > pt _ Point x: 100 y: 200. > > or > pt _ Point new. > pt setX: 100 setY : 200 > > Both are correct, but one is more elegant. > > Hint try 10 @ 'hello' > is always interesting to invoke on people, something about what is a > language definition, versus usage of the definition. This last one is surprising... Thank you John for these explanations.

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Re: Celeste is cool...
by danielv＠netvision.net.il 29 Sep '01

29 Sep '01

Using 3.1a, I use the menu gotten over the category list. You're looking for the options next to last. Anyhow, Celeste will ask you stuff as you go along, you don't have to configure it explicitly... Have fun. Daniel gafisher(a)sprynet.com wrote: > Hey, Göran! > > Probably like many others, I use whatever I'm working on at the moment. However, that DOES bring up a question: I've had no trouble using Celeste in 2.8, but in 3.0 I can't get to the "choose smtp server" et al setups. Can anyone show me how dense I am by telling me what obvious thing I'm missing? (-: > > Gary > > > squeak-dev(a)lists.squeakfoundation.org wrote: > > Hi guys! > > I just noticed that there is a line in emailheaders (well, I knew that > already but...) looking like this: > > X-Mailer: Clientid > > ...so, a custom filter like: > > m textHas: 'X-Mailer: Celeste' > > ...discovered that there are a few faithful (Anthony, Lex, Bruce, > Stephen, Daniel and myself for example) out there! :-) Cool. > > regards, Göran

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Re: Localization in code
by Richard A. O'Keefe 29 Sep '01

29 Sep '01

"Andreas Raab" <Andreas.Raab(a)gmx.de> wrote: 'The value of <name> is <value>' printWith: {#name. 'cargo'. #value. cargo}. Wouldn't #('The value of ' name ' is ' value '.') printWith: {#name -> 'cargo'. #value -> cargo}. or #('The value of ' name ' is ' value '.') printWith: #name -> 'cargo' with: #value -> cargo. be more Smalltalky (Smalltalkish?). I rather like having messages in separate files because + You can give them to someone to translate who doesn't have to know about the programming language involved. + A program can dynamically switch languages (quite handy when a lecturer's preferred language isn't the same as a student's preferred language). + Variant: the same image can provide messages in English when run by me or Maori, Chinese, whatever when run by a student who'd prefer that. (Yeah, dream on...) The student wouldn't have to start a different image or load a special change-set. + Messages only have to be edited in one place however many places they are used. Any technique which can do the same would be as welcome. (Just because a student is good at English doesn't mean he or she wouldn't rather work in his or her own language.) Ideally, we'd have a natural language generation system rather like ILEX so that no translation as such would be involved at all. That kind of stuff is getting _very_ close to ready for use.

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Fonts problem in Squeak
by Christian Langreiter 29 Sep '01

29 Sep '01

In a fully updated 3.1 image, I ´try to install a Truetype font via ... "TTFontReader installTTF: 'c:\winnt\fonts\arial.ttf' asTextStyle: #Arial sizes: #(24 60)" So far, so good. However, as soon as I try to actually put the font to use (by clicking to the System Font menu entry), I get a "Bad BitBlt arg (Fraction?)" error as soon as the font selection menu is about to be displayed. If I proceed, nothing happens. BTW, is there any other way to get Truetype fonts into Squeak? All the methods I've tried (as described on this ML and the Swiki) either give errors or a obsolete. Andreas Raabs TTF-to-file-in converter produces Smalltalk code for old Squeaks &c. Will is this font issue destined to remain my single biggest Squeak annoyance forever? Best regards, -- Chris

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Zurgle Project Update
by Jim Benson 29 Sep '01

29 Sep '01

I've gotten a couple of request off list asking where I'm at in Zurgle land. I've put together a little page and some what of a code "snapshot" of where I'm currently at. Here's a screenshot: http://people.we.mediaone.net/trade/Zurgle/LunaScreenShot.jpg (283K) Here's where you can go get some code: http://people.we.mediaone.net/trade/Zurgle/ZurgleUpdate.htm This isn't meant as a formal release, just here's where I'm at in development, warts and all. If there are things you're looking for in particular, let me know. I must say at this point, I'm quite a bit happier in this development environment than in the stock version. I'm surprised at how different Squeak feels with just a few simple modifications. BTW, you'll need to bump up to 32 bit color for the colors to come out correctly. The screen shot also fiddled with font sizes, and added a background. My background code tweaks are in there, but you'll have to supply your own background image :) I need to do a little code trimming and pruning, but next up are combo boxes, grouping of radio controls, and various dialog boxes. Jim Benson United We Stand

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Re: Desired Archive behavior w/r/t absolute paths?
by danielv＠netvision.net.il 29 Sep '01

29 Sep '01

My .02 Shekels - When you see such files, explain the situation to the user, and let him specify the effective root (he can specify the real root, if he's sure). Daniel PS - The archiver is very nice, I like it ! Ned Konz <ned(a)bike-nomad.com> wrote: > The Zip archive format allows absolute pathnames (i.e. those starting with > '/'). Most people don't use them, but it's generally possible to do so > (possibly inadvertently). > > My ArchiveViewer allows extraction of all the files in an archive (which may > have a mixture of absolute and relative names) into a particular directory. > The obvious way to handle this is also a potentially dangerous one: use the > given directory as the root for the relative files, but extract the absolute > ones to their desired path. i.e., if you have an archive with the files > (trailing / denotes a directory): > > /a/ > /a/b > c/d/ > c/d/e > > and extracted to /tmp, you would get: > > /a/ > /a/b > /tmp/c/d/ > /tmp/c/d/e > > Under Unix and some Windows NT systems, file permissions may protect files > you don't own from being clobbered. > > The other obvious way to handle the problem is to make all files relative > whether or not they started out that way in the archive, so we'd extract the > above as: > > /tmp/a/ > /tmp/a/b > /tmp/c/d/ > /tmp/c/d/e > > If you wanted to extract to the root, of course, that's up to you and your > filesystem security. > > I'm leaning toward the second strategy; does anyone have a preference on this > that they'd like to share? > > -- > Ned Konz > currently: Stanwood, WA > email: ned(a)bike-nomad.com > homepage: http://bike-nomad.com

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