Squeak-dev September 1999

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133 participants
357 discussions

Fraction hackers...
by Dan Ingalls 02 Sep '99

02 Sep '99

In update 1400, I changed the implementation of Fraction = to tolerate improper fractions. I think it's the best fix to make (1/2) = (3/6). VW fails this, and Squeak used to as well (for the same reason). If you like to work with Fractions, I would appreciate it if you would check that I haven't broken anything obvious. Thanks. - Dan

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[q] image/class importers
by Jeff Szuhay 01 Sep '99

01 Sep '99

The recent discussion about having multiple images of Squeak got me thinking (yes, a dangerous think for my newbie little mind...) What are the facilities in Squeak for intelligent class importing/exporting? I'm thinking along the lines of exporting an entire class and all its inheritors and ancestors. Whenever there are discrepancies in a class definition, some kind of "diff" window pops up and lets the use overwrite, ignore, or edit the differences. Is this currently in Squeak? If not, is anybody working on it? 8-) --************************************************** Jeff Szuhay <mailto:jeffs@pstnet.com> Lead Macintosh Engineer voice: 412/271-5040 x227 Psychology Software Tools <http://www.pstnet.com/>

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Re: Problems with Win32/WinCE VMs - backing out of changes
by Marcel Weiher 01 Sep '99

01 Sep '99

> From: "Peter Smet" <peter.smet(a)flinders.edu.au> > > From: Dick Karpinski <dick(a)cfcl.com> > > >A second mystery to me is why Filein operations are irreversable. What's > >the problem? I know how to write the reversing instructions when I do the > >damage in other systems. Why do people put up with being unable to > retreat? > > > Ever tried a clean uninstall of just about anything on Windows? 90% of the > time > I find the uninstallers require manual help ie: > > "some files could not be removed" > > So, you could force developers to write uninstall code, as occurs for > Windows, but > this doesn't seem to be terribly successful. The comparison with the Windows mess is really quite illuminating, because it shows that the current situation is not really adequate ( "hey, it's just like Windoze!" ). I tried protected projects and they didn't really work for me (I ended up with a hosed image and strange change-sets). I don't have a clear analysis of what happened because I was delibaretely not careful about it. After all, if this protection only works if you're really, really careful, then it's not very useful protection. Wether this is fixable, I don't know. I suspect it isn't without much effort because the problems seems to have been approached from the wrong angle, IMHO. Anyway, the mutable-image problem is probably the second biggest obstacle to my actually using Squeak for productive, right after the integration problems. The way I work around it now is to have throw-away images to work on risky code-bases. Not exactly an optimal solution, but the only at least partially workable one I've found so far, and I think I am not alone. Of course, many of the advantages of the integrated image approach are lost in this way. I guess it wouldn't be quite as bad if images were much smaller. After all, it really is rather silly to have 5 or more copies of the image, which are probably 99% identical. The obvious way to solve this (for me anyway) is to share copies of the image, using some sort of copy-on-write technique that is constructed in such a way that it is impossible to modify the shared copy (for that warm, fuzzy feeling). Instead of a large mutable image with smaller chunks that can be stored separately or protected (more or less), you have a large protected section and small, mutable 'images'. With a well implemented copy-on-write scheme, this doesn't have to have any impact on 'image-style' development. It can also be the starting point for a more complete implementation (Hans Martin's Collage). Marcel

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Squeak 2.5 problems with changing font size.
by David LeBlanc 01 Sep '99

01 Sep '99

As usual when installing a new version of Squeak, I evaluated: TextStyle changeDefaultFontSizeBy: 2 so I could see what i'm doing and saw the following problems: The "Getting Started" and "Welcome To" windows had a larger title which overflowed the title bar on the top and the bottom. The "Getting Started" and "Welcome To" windows both gained a blank space between the title bar and the rest of the window. At first it shows the background color, but if you move it it shows artifacts of what might have been under the window. The Help/Preferences pop-up menu does not resize properly. As it first displays all of the lines of text in the pop-up are truncated on the right. If you resize, the lines of text don't and remain truncated and all you see to the right of them is blank window. Also, the balloons that pop-up over each line item are using something like a 6 point font which is totally unreadable. Opening and closing the "Play With Me" windows causes their titles to resize and thus the closed window ?icon? - except they resize themselves arbitrarily and truncate their label. The "set font" and "set style" menu items either don't seem to do anything or sometimes they make the font as small as humanly possible - thus unreadable. Clicking on the sqeak documentation hyperlink in the "Getting Started" window causes a Scamper browser to come up and do nothing except show some messages in the Transcript about data being slow and then a data byte count. The Scamper window remains blank. The documentation in "Getting Started", "Welcome To" and "readme.txt" are all mac-centric. So, in fact, is much of the global menu help stuff. I am using Windows NT and don't have a cmd key on my keyboard. ==================================== I think some of this can be fixed by closing and reopening some of the offending windows, but I don't know how to do that. Others just seem to be glitches. Dave LeBlanc

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RE: reversing fileins (was More Benchmark Results + Problems with Win32/WinCE VMs)
by Glenn Krasner 01 Sep '99

01 Sep '99

The VisualWorks parcel load/unload mechanism includes this kind of "version stack". You may want to check it out by way of example. glenn At 01:07 PM 9/1/99 -0400, Norton, Chris wrote: >Hi Folks. > >Regarding reversible fileins, Dan Ingalls [Dan.Ingalls(a)disney.com] wrote: >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >"First, although, as Dwight points out, a fileIn can have any kind of >executable code in it, most are pretty well behaved (add/remove methods, >instVars, classVars, classes), and most of these changes could be reversed >without a huge amount of bookkeeping. It might be worth doing." >~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > >Good point! As a person that often uses the filein mechanism, I would >suggest that "normal" fileins (fileins that don't execute any wild new code) >are far more prevalent than the latter. I'm not a change set expert, but >isn't it the case that the executable code performed during the filein >process is stored in the post script section of the change set? It might be >easy to mark change sets as "those containing executable code" and "those >without executable code" by doing a quick parse of the post script section >of the change set. Having armed the change set browsers with the ability to >differentiate between the two cases, one could then allow the change sets >that do not execute wild new code to be removed from the image. > >Of course, the process of reverting a change set out of your image would >require that you have not compressed your sources since the change set was >filed in. It may also be the case that change sets that remove classes and >class variables may have to be disallowed from the reversion process. After >all, what would you initialize the "deleted" class variables to? > >This is interesting food for thought (it's lunchtime on the US east coast!). > > >Cheers! >---==> Chris >> > > >

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RE: More Benchmark Results + Problems with Win32/WinCE VMs
by Norton, Chris 01 Sep '99

01 Sep '99

Hi Folks. Regarding reversible fileins, Dan Ingalls [Dan.Ingalls(a)disney.com] wrote: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ "First, although, as Dwight points out, a fileIn can have any kind of executable code in it, most are pretty well behaved (add/remove methods, instVars, classVars, classes), and most of these changes could be reversed without a huge amount of bookkeeping. It might be worth doing." ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Good point! As a person that often uses the filein mechanism, I would suggest that "normal" fileins (fileins that don't execute any wild new code) are far more prevalent than the latter. I'm not a change set expert, but isn't it the case that the executable code performed during the filein process is stored in the post script section of the change set? It might be easy to mark change sets as "those containing executable code" and "those without executable code" by doing a quick parse of the post script section of the change set. Having armed the change set browsers with the ability to differentiate between the two cases, one could then allow the change sets that do not execute wild new code to be removed from the image. Of course, the process of reverting a change set out of your image would require that you have not compressed your sources since the change set was filed in. It may also be the case that change sets that remove classes and class variables may have to be disallowed from the reversion process. After all, what would you initialize the "deleted" class variables to? This is interesting food for thought (it's lunchtime on the US east coast!). Cheers! ---==> Chris >

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Re: Code Ports and Copyrights
by Blake McBride 01 Sep '99

01 Sep '99

At 09:00 AM 9/1/99 -0700, you wrote: >I have ported several programs that were available on the >Smalltalk Archive (hanoi, wires, ropes, USA) as part of my >learning process. > >My product is based on someone else's original work, but >includes (sometimes substantial) changes to make it work in >Squeak. > >I have received permission to use some code, is it enough >to state in the comments that the code is based on <foo> >written by <bar> or do I need to specify the differences >between the original and my version. > >If someone then asks me if they can use this new program >can I give them permission for all of it or just my part? > >Thanks, > >John-Reed Maffeo >Mesa, Arizona I am not an attorney but I have dealt with software legal issues for many years so take this as you may. If someone marks their software with a copyright message it's copyrighted period. Once you gain access to copyrighted software you cannot do anything with ANY part of it without express permission. You can't use any part of copyrighted software regardless of how much you change it or how small a piece without express permission. "based on" messages mean nothing and are only a courtesy (unless the author requires it as part of his permission). Further, you can't distribute (give copies) of any part of any software you don't have rights or permission to. --blake ------- Download source code to my Dynace Object Oriented Extension to C and Windows Development System from: http://www.florida-software.com/algorithms Blake McBride (blake(a)florida-software.com) Algorithms Corporation - 615-791-1636 - USA

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RE: Code Ports and Copyrights
by agree＠carltonfields.com 01 Sep '99

01 Sep '99

> If someone marks their software with a copyright message it's > copyrighted > period. No, if it was fixed in tangible media after 1988, its copyrighted, regardless of whether or not there is a copyright message. (This is true for most, but not all countries). >Once you gain access to copyrighted software you > cannot do anything > with ANY part of it without express permission. Not so! You can make fair use, and you can take any non-protectible elements. Further, you can do other things, pursuant to 17 U.S.C. section 117 in many, but not all cases. Further, consent can be implied as well as express. But this is all hazardous and fuzzy territory -- do not try to make these decisions unaided by competent counsel, probably a software specialist. > You can't > use any part of copyrighted software regardless of how much > you change it or how small > a piece without express permission. No, this isn't so. Size CAN matter for purposes of fair use. But the author's advice is far more often going to be right than wrong. Always ask a lawyer if you are relying upon a fair use or implied consent theory. > "based on" messages mean nothing > and are only a courtesy (unless the author requires it as part of his > permission). This is absolutely true in the US. Outside the US, however, the failure to give credit can be a violation of so-called "moral rights" or "droits moral," which are actionable protections given to the AUTHOR of the program independent of the copyright in many EC and other countries. International publication without due care for clearance of IP is a risky business these days. > Further, you can't distribute (give copies) of any part of > any software you > don't have rights or permission to. This is mostly correct. A copyright owner's exclusive rights does include the exclusive right to distribut. However, some copy-giving can be blessed under some circumstances -- another "do not try this at home" issue. Again, please do not take this as legal advice for any particular matter. Each of these issues are highly fact-specific in terms of their results, and subtle differences in facts can swing a decision 180 degrees. Rely only upon advice of competent counsel who has studied your particular facts and applied the applicable law to those facts. Hope this doesn't ruin anybody's day. Best, A

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Re: Problems with Win32/WinCE VMs - backing out of changes
by Marcel Weiher 01 Sep '99

01 Sep '99

> From: Bob Arning <arning(a)charm.net> > > On Wed, 1 Sep 1999 15:41:18 +0200 Marcel Weiher <marcel(a)system.de> = > wrote: > >I guess it wouldn't be quite as bad if images were much smaller. =20 > >After all, it really is rather silly to have 5 or more copies of the = > =20 > >image, which are probably 99% identical. > > Marcel, > > While not wishing to argue against improvements in the current = > architecture, "silly" seems an inappropriate criticism. The effect of lugging 4-6 MB around when the changes are typically on the order of a couple of KB, a wastage factor of 1:1000 is silly to me. Copying the images + changes files takes a noticable amount of time on my machine, when it really shouldn't. Your mileage may vary. > Given disk = > prices on the order of US$0.04 per megabyte, the cost of storing an = > additional image is well under a dollar. I keep lots of images around, = > both current and earlier releases, both pristine and modified. Cost of storage is really not the problem. > Often I = > have more than one up and running concurrently, each particularly = > suited to the task at hand. I don't see it as a problem, rather I = > leverage the capacity of my computer to provide an additional level of = > isolation between potentially conflicting threads of development. The situation gets worse with multi-tasking because all that memory is 'dirty' from the point of view of the operating system, so each additional Squeak task gets the *full* RAM penalty, just like current Java VMs do (Of course, Java's footprint is bigger, so the problem is worse, but structurally it's the same problem). I consider the good VM systems with mapping, protection, sharing etc. one of the major benefits of modern UNIX systems (NT to a lesser extent); they enable a lot of useful functionality and it's a shame to lose it again. > Duplicating that level of isolation within one image may take a = > non-trivial effort to get completely right. With the current approach (try to split of sub-images, retract changes etc.) it is probably quite hard, maybe impossible. A slightly different approach based on reading/mapping non-mutable structures into a (smaller) mutable image should be easier, especially if initial development is done on a machine with real virtual memory that can be used to guard against/track accidental writes. I'd be willing to give it a shot if I had assistance from a knowledgeable Squeak/VM hacker. Marcel

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RE: More Benchmark Results + Problems with Win32/WinCE VMs
by Raab, Andreas 01 Sep '99

01 Sep '99

Dean, > Interesting side note: This is about 30% faster than > my 450 MHz Pentium II at work. > Check out how much L2 cache you have in the machines - it could make a huge difference. > Now on to the Win32 VM stuff. Running on the P133 machine (a > Sharp Widenote), mouse clicks were definitely getting lost when > running in Morphic, and I also experienced long periods of un- > responsiveness - not as bad as on the Casio E-105, but several > seconds anyway. This behavior was not apparent under the standard UI. > Lost mouse clicks are definitely not a Win32 issue - it happens on all machines that are slow enough. The events are received by the VM but Morphic just does not poll often enough to get the mouse clicks (e.g., when the mouse gets down and up inbetween two poll cycles you have a lost mouse click). I'm not sure about the long pauses but I suspect that this is no Win32 issue either. I'd recommend looking at the image side and try to figure out if the problem might be GC related (wild guess: having a big image and not enough memory might cause the system to swap like hell on full GCs). Andreas -- +===== Andreas Raab ========= (andreasr(a)wdi.disney.com) ==+ | Walt Disney Imagineering Phone: +1 818 544 5016 I I Glendale, CA Fax: +1 818 544 4544 I +======< http://isgwww.cs.uni-magdeburg.de/~raab >========+

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