Squeak-dev June 1999

squeak-dev@lists.squeakfoundation.org

139 participants
408 discussions

FMP, the game
by Bob Arning 28 Jun '99

28 Jun '99

FMP is a not too complicated strategy game where players compete to gather ore from the surface of a planet. http://www.charm.net/~arning/FMP.28Jun344pm.cs Cheers, Bob

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Strange behaviour of messages with mismatched arguments..
by Peter Smet 28 Jun '99

28 Jun '99

I was investigating some weird behaviour in my program (which is about the only kind of behaviour I am getting) when I noticed that messages where the selector and the arguments don't match result in strange things. For example: | b | b := Bag new. (Message selector: #add: arguments: #(1 2 3)) sentTo: b. b. The bag will end up adding the selector to itself instead of raising an error message. If you send it an empty array of args the same thing happens. Is this the intended behaviour? Peter

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Java Look and Feel Design Guidlines
by John-Reed Maffeo 28 Jun '99

28 Jun '99

I found this link while looking for information about interface design. It might be helpful to other newbies. http://java.sun.com/products/jlf/dg/index.htm John-Reed Maffeo

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Info required
by Nagananda A 28 Jun '99

28 Jun '99

Hello, This is Nagananda A. from Bangalore , India. We need to do a project in porting Smalltalk to C. Can you tell me whether I can use Squeak tool for this purpose. If so, how can i use Squeak? Please give me more details. If not can you please suggest me some utility / resource for executing this project. Thanks in advance. Regards, Nagananda email : anaga(a)wipsys.soft.net

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Re: Info required
by Bruce ONeel 28 Jun '99

28 Jun '99

Hi, Without knowing the details about what you are trying to do this will be a bit hard. Where Squeak might help you is that it does have a Smalltalk to C compiler/translater. (I hope I get this right) If you have a smalltalk method which uses a slightly limited form of smalltalk then you can convert it to a C primative and build it into the VM. Probably with some hassle you could take this bit of C code and make it somewhat standalone. I've never tried. What Squeak does not include is a full up, here is my mass of Smalltalk classes, build me a functionally equivalent C program. That's a slightly hard problem :-) My guess is that the best way to do this is to look at the design of the existing smalltalk program, do a new design which takes into account the differences between smalltalk and C, pray that the existing program doesn't take advantage of any things easy to do in smalltalk and hard to do in c, and then rewrite from scratch a new C program. Others, I'm sure, would have different ideas :-) cheers bruce "Nagananda A" <anaga(a)wipsys.soft.net> wrote: > Hello, > This is Nagananda A. from Bangalore , India. > We need to do a project in porting Smalltalk to C. Can you tell me > whether > I can use Squeak tool for this purpose. If so, how can i use Squeak? > Please > give me more details. > > If not can you please suggest me some utility / resource for executing > this project. > > Thanks in advance. > > Regards, > Nagananda > > email : anaga(a)wipsys.soft.net ---- Reality is 80m polygons - Alvy Ray Smith Bruce O'Neel - beoneel(a)mindspring.com http://homepage.iprolink.ch/~bioneel/beo/beo.html - daily stuff

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Subsumption and OO
by Peter Smet 28 Jun '99

28 Jun '99

While musing on asynchronous events and distributed control, I had a look at the subsumption architecture (SA) of Rodney Brooks, for robots with no centralized control or representation of the world (very radical at the time he first introduced it). I wondered if OO is a subsumption architecture or not, or if his ideas could be adapted to OO. In essence, SA uses layering. Each layer is a bunch of finite state machines (FSM, which are like objects) that receive 'messages' or 'events' and can act on them by issuing output signals (usually to an actuator device). For example, the first layer might implement the behaviour 'breathing' or 'avoiding obstacles'. Higher layers can wrest control of the lower layers, and so turn 'breathing' into 'singing' or 'talking'. You get the idea. The important bit is that each layer uses the one below it, and that if anything in a higher layer breaks (or the higher layer is simply not active) the lower layer automatically gains control. This last bit, and the independence of the components, is where the robustness comes from. My immediate thought was that OO and Software engineering do this already. For example, the lower layer can be thought of as the basic method in an ancestor, and the higher layer is the same method, overidden to provide new behaviour in the descendant. At a higher level, software is often layered, so that the drawing primitives are on the bottom layer, and windowing functions on a higher level. However, subsumption is subtley different. Time is important. The problem with method overriding is that the behaviour is changed for all time, with no reverting to the original method. For one layer to gain control over a lower layer, it has to actively suppress the lower layer. It only has control while it is supressing. It is like having a method that says, whenever the screen is orange, print 'layer 2'. As soon as the screen is not orange, the method does nothing, but the ancestor method magically gets invoked to print 'layer 1'. It is more like a wrapper, where the outer object tests to see if the screen is orange. If it is, it invokes its method, otherwise it delegates to the wrappee. Or like the state pattern, where the state object gets swapped whenever the screen changes colour. But these concepts are more brittle - if the wrapper dies or the state-swapper dies, the basic behaviour dies with it. In the subsumption architecture, the lower layer is automatically reinvoked. It seems as though you will need to run the high and low layer objects asynchronously and in parallel to get the robustness of the SA. Many threads all simultaneously fighting for control seems to get the effect. I was going to add some more, but it's time to go home. Any thoughts on using the subsumption architecture to make OO programs more robust, and how it would be done? Peter

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Re: [Unix] Alice Objects.zip
by Bert Freudenberg 26 Jun '99

26 Jun '99

Ooops - attachment didn't work. Trying again ... -------------------- Hi Unix Squeakers, while playing with Alice and the downloaded models in Objects.zip I encountered a lot of "file not found" errors ... It turns out many of the texture (.bmp) and geometry (.vfb) files are not named correctly. HELLO WORLD: CASE DOES MATTER! Anyway, here's a shell script that scans all model files (.mdl) for references and renames the .bmp and .vfb files accordingly. Run it from the model root directory (the one containing subdirs Alphabet, Animals etc.) Have fun, /bert PS: Anyone interested in the fixed archive? Content-Type: APPLICATION/x-sh; name="fixalicefiles.sh" Content-ID: <Pine.LNX.3.96.990626221728.14432F(a)balloon.cs.uni-magdeburg.de> Content-Description: Attachment converted: Anon:fixalicefiles.sh (????/----) (0000AD10)

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[Unix] Alice Objects.zip
by Bert Freudenberg 26 Jun '99

26 Jun '99

Hi Unix Squeakers, while playing with Alice and the downloaded models in Objects.zip I encountered a lot of "file not found" errors ... It turns out many of the texture (.bmp) and geometry (.vfb) files are not named correctly. HELLO WORLD: CASE DOES MATTER! Anyway, here's a shell script that scans all model files (.mdl) for references and renames the .bmp and .vfb files accordingly. Run it from the model root directory (the one containing subdirs Alphabet, Animals etc.) Have fun, /bert PS: Anyone interested in the fixed archive?

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ObjectExplorer & MorphcWrappers
by Leandro Caniglia 26 Jun '99

26 Jun '99

Are you using MorphicWrappers? If so, just drag any item from the ObjectExplorer hierarchy (thanks Bob!) and place it in the World. Leandro PD: The current beta version of MW24 is available from: http://www.dm.uba.ar/mathMorphs and also from http://sugarweb/Miniatures/files/Morphic/MW24.22Jun1048am.zip Content-Type: application/octet-stream; name="ObjectExplorerMWExtension.26Jun145pm.cs" Content-Disposition: attachment; filename="ObjectExplorerMWExtension.26Jun145pm.cs" Attachment converted: Anon:ObjectExplorerMWExtension.26Jun (????/----) (0000AD0F)

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Re: Screenshots
by ohshima＠is.titech.ac.jp 26 Jun '99

26 Jun '99

Hi, I found that someone (Torsten Bergmann?) kindly put the image of Squeak running on a PDA. I'd like to express my thanks. However, now we have a better PDA and better screenshot of Squeak running on the PDA, so I already put the image on the "Screenshot page". The problem is that I can't figure out I should remove the former one or not. Please notice me what I should do with that. Thank you. OHSHIMA Yoshiki Dept. of Mathematical and Computing Sciences Tokyo Institute of Technology

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