Squeak-dev July 1999

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139 participants
367 discussions

ListServer? A couple of ideas
by Chris Cunningham 02 Jul '99

02 Jul '99

I was wondering if anyone had thought about implementing a ListServer in Squeak. Now that Squeak and send and receive email, it would seem to be possible to implement this. If we had a ListServer in Squeak, then it could be connected to a Swiki and produce up to the minute archives list activity, possibly automatically indexed by subject and date. It at least seems possible. Then, maybe the formats for the Swiki could be changed to not allow edits, but to allow responses or new topics, which could be sent out via the ListServer to all subscribers. Two ways into the list. Then, if someone implemented a News server, we could tie that into the foregoing mismash, and have 3 interfaces into the lists, satisfying almost everyone (i.e., have your favorite interface to the list). The News interface would likely be very nice to those people who have to pay by the minute to read this stuff, too <shudder/>.

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Re: On Reuse
by Les Tyrrell 02 Jul '99

02 Jul '99

This is a pretty huge topic... luckily, there is a fairly extensive body of literature on it, that is, literature that actually knows what it's talking about. There is also a fairly extensive body of literature that parrots some sort of shadow of knowledge about the topic. Which is not to say that the statements you see are untrue, it's just that you don't come away from them understanding what the problem was. If you'd like a really good introduction to this topic, then I'd strongly reccomend Edward Berard's book, which I believe is titled "Design of Object-Oriented Software". It is one of the extremely few software books with EXTENSIVE references, usually three or more for each item of discussion. This makes a great starting point for your own understanding of the subject. Not for the faint-hearted, but if you really want to dig in on the subject I think this is one of the best places to start. Beware authors who state but do not support their own claims with extensive references- when I see those, I think they're just making it all up. For example, there is this "7 +/- 2" rule about complexity that you often see in various contexts. But noone ever mentions what basis exists for it, so it's considered to be a rule of thumb. But there really was research done on this, and there really is an original source in the scientific literature for this "rule of thumb". To me, the astonishing thing has been how old much of this literature is- you would assume that it is some sort of brand new topic, but you find the basis for this stuff originating not in the 80's, or the 70's, or even the 60's, but back in the 50's and even back in the 30's. By the mid-80's, it appears that reuse had become a fairly mature subject, and sufficiently well understood to be effectively carried out in environments using procedural languages. From what I've seen, I'd have to say that reuse ceased to be a topic of research by that time- from then on, it's been an issue of successfully applying that knowledge. Unfortunately, this is still a big issue as the problems in applying reuse are primarily cultural rather than technical in nature. les

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Re: On Reuse
by Peter Smet 01 Jul '99

01 Jul '99

> >It may save people lots of time if we have a list of Squeak enhancements at >the Swiki. Just a title and one line comment for each thing. We could then >get into the habit of quickly perusing this list BEFORE we embark on our >next 'interesting project'. There, I've done it. There is a new page at the Swiki called "Been there, done that". I have hurriedly listed a few things there. Please add to this list. Remember, this is for doing a quick scan so keep descriptions to one line or less. Peter

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Re: [ENH] OS-level events
by Marcel Weiher 01 Jul '99

01 Jul '99

> From: "Lex Spoon" <lex(a)cc.gatech.edu> > In Morphic, they're actually already gone. That's why you can scroll a text pane > and have your BouncingAtomsMorph keep bouncing around while you do it. Of > course, the logic for menus and for text highlighting and things like that, which > take a long time to execute, are made more complicated because they have to store > intermediate states in instance variables--the extra interactivity is not for > free. Wouldn't that added complexity go away if an asynchronous message/event delivery model were used so that these tasks could be coded as plain methods that wait for messages to arrive? Marcel

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New Smalltalk on-line mag
by Peter Smet 01 Jul '99

01 Jul '99

Here is a link some of you may find interesting. There is a really well-written article on exception handling, and some other good stuff: http://www.objectpeople.com/smalltalkchronicles/ Peter

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dissappearing thumbnails on Swiki..
by Peter Smet 01 Jul '99

01 Jul '99

I just looked at the screenshot page on the swiki, http://minnow.cc.gatech.edu/squeak.683 and it seems (at least on my browser) that all the thumbnails have disappeared. These were put up by Bert I think. Are the links broken or is it my browser? When I attempt to edit the page to find out what is going on, I get the following error: subscript is out of bounds: 3276 The number changed on the second attempt: subscript is out of bounds: 2580 I just realised the error is a lot more general - I can't load ANY page without getting an error... Any ideas? Peter

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Re: Funny message at top of Swiki page
by Bolot Kerimbaev 01 Jul '99

01 Jul '99

let me guess... you're using netscape, and you did something like: http://host/myswiki which netscape took for the directory, and thus opened: http://host/myswiki/ and swiki understood that and showed page myswiki.1 but now links are all relative to ... /myswiki/ and look like: http://host/myswiki/myswiki.2 swiki server informs you of that to avoid it, use myswiki.1 bolot On Thu, 1 Jul 1999, Stephen Pair wrote: > When hitting the Swiki, I got the following message at the top of a page: > > Your original url has a slash after it. Please remove it. > HTTP/1.0 200 OK Content-Type: text/html > > ...there didn't appear to be any slash following the URL and I got to the > page (the screen shots page) by following a link from the front page. > > Anyone know why this is happening? > > - Stephen > >

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Re: Funny message at top of Swiki page
by Mark Guzdial 01 Jul '99

01 Jul '99

If you visit http://minnow.cc.gatech.edu/squeak instead of http://minnow.cc.gatech.edu/squeak.1, some browsers will think that you're visiting a directory and will stick a slash at the end of your URL, e.g., http://minnow.cc.gatech.edu/squeak/ Now, no relative links work right, e.g., references to squeak.23 become http://minnow.cc.gatech.edu/squeak/squeak.23. We currently catch it as a special case, and warn the user. Mark >When hitting the Swiki, I got the following message at the top of a page: > >Your original url has a slash after it. Please remove it. >HTTP/1.0 200 OK Content-Type: text/html > >...there didn't appear to be any slash following the URL and I got to the >page (the screen shots page) by following a link from the front page. > >Anyone know why this is happening? > >- Stephen -------------------------- 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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Programming with Tuples (was On Reuse)
by Mark Guzdial 01 Jul '99

01 Jul '99

I've been thinking about reuse, and integration, for a few months now from the context of maintaining the PWS. It's almost a holiday weekend (for us in the U.S.), so perhaps I might waste some bandwidth describing some of these ideas. I doubt that the solutions I've been considering are at all new, but perhaps someone could kindly point me toward similar thoughts. A bunch of people on the PWS list are generating some wonderful additions to the system. However, these additions often conflict with one another. The most common conflict is that two additions modify the same method, but one modifies a couple lines at the top (for example), while the other modifies a couple of lines at the bottom. One answer is, "Better factoring." If that one method were several smaller methods, then each contributor would only be modifying unit methods. That may be, but it seems to me that there is no one factoring that would mean that *all* possible enhancements/additions/modifications to the system would only touch unitary methods. There's probably a theorem about O-O systems that makes this case somewhere. While the PWS could clearly use better factoring, even if there isn't a perfect factoring, I've been wondering about the general case. How can I add or replace functionality in units-smaller-than-a-method, without disturbing existing functionality? I've been thinking about units of code not as lines, but as tuples. Methods could be assembled from these tuples. Each tuple has three elements: ({A statement or guarantee of purpose}, {A predicate to determine ordering}, {An expression}) ------<example> Let me take an example from PWS to describe what I mean. The portion of code in ServerAction that responds to a request with a file assembles a header might look something like this in Tuple form: (SendSuccess, First, request reply: PWS success) (SendType, After SendSuccess, request reply: PWS textContent) (SendFile, After SendType, request reply: (FileStream fileNamed: pieces) contentsOfEntireFile) Recently, someone wanted to serve GIFs, and we realized that we were still (after all this time!) only wired to send text files in normal server mode. (Ted fixed it a long time ago from Swikis.) I'd love to have been able to distribute the single Tuple, which wouldn't modify anything else in the method: (SendType, After SendSuccess, request reply: 'Content-type:',(MIMEDocument guessTypeFromName: pieces), PWS crlf) Further, someone else came up with something relevant to put in the header, as I recall, to prevent proxy servers from caching an edit page. I don't recall the exact details, but perhaps it could be distributed as a single tuple like this: (SendMeta, After SendType and Before SendFile, request reply: 'do not cache me!') -----</example> This is different than just methods and factoring, because of the ability to insert new functionality by modifying the predicates, but without rewriting the whole method. It's similar to production rule systems, in some sense, but the ordering can be determined before execution, so it can be much faster. There are lots of holes here. For example, how small does that expression unit have to be to be useful? Do we end up writing assembly code, for example? But again, it's nearly a holiday weekend, so perhaps you'll excuse some half-baked discussion. I haven't read much of Bertrand Myer's work, but my guess is that he's someone who's probably worked out things like this. Any suggestions? Thanks, Mark -------------------------- 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: [ENH] OS-level events
by Peter William Lount 01 Jul '99

01 Jul '99

Hi Lex, What replaces the controller loops in Morphic? Peter ---------- From: Lex Spoon <lex(a)cc.gatech.edu> To: squeak(a)cs.uiuc.edu Subject: Re: [ENH] OS-level events Date: July 1, 1999 10:29 AM "Peter William Lount" <peter(a)smalltalk.org> wrote: > One of my questions is "what will happen to the Controller loop" with an > event based Smalltalk"? I guess that it goes away and gets replaced by > something like the NSApplication loop. I'll have to explore some event > based Smalltalks to find out... What are you guys planning to do with the > controller loops? > In Morphic, they're actually already gone. That's why you can scroll a text pane and have your BouncingAtomsMorph keep bouncing around while you do it. Of course, the logic for menus and for text highlighting and things like that, which take a long time to execute, are made more complicated because they have to store intermediate states in instance variables--the extra interactivity is not for free. Lex

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