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79922 discussions

Use of Squeak in Class
by wallingf＠cs.uni.edu 12 Jan '98

12 Jan '98

I am teaching a course this semester on software systems, a large component of which is the design of user interfaces. Are any of you using Squeak in any courses as a tool for critiquing or building interfaces? If so, I would be interested in hearing about your experiences. None of my students will have programmed in Smalltalk before, so I will be getting them started during the course. As is standard, I would be happy to summarize the responses I receive back to the list for everyone's consideration. ---- Eugene

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Java VM inside Smalltalk
by Alejandro F. Reimondo 12 Jan '98

12 Jan '98

Who knows where can I find the Smalltalk that have a Java VM inside the Smalltalk VM ? Is it the Little Smalltalk? I am interested in look at it to evaluate the posibility to build a Java VM inside the Squeak VM. Thanks. Ale.

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Windows API calls for Squeak 1.23
by Alejandro F. Reimondo 12 Jan '98

12 Jan '98

I've implemented API calls for Squeak 1.23 under Windows. Framework supports source compatibility with Visual Smalltalk 3.1x and is expandable to support compatibility with Dolphin Smalltalk. You can download the package (300kb) from http://www.sugarweb.com/Miniatures/Files/SqApis.Zip or you can visit http://www.sugarWeb.com to see what is done in Smalltalk in Argentina SUGAR is not an adition to Java, it is Smalltalk User Group of ARgentina. :-) Follows readme file ------------------------------------------------------------------ Windows API Calls for Squeak 1.23 --------------------------------- Version: 0.7 This package works correctly but is incomplete and not fully debugged. Please report bugs and questions to Alejandro F. Reimondo at alereimondo(a)sugarWeb.com Feel free to visit http://www.sugarweb.com (Smalltalk User Group ARgentina) for more recent versions and other works on Smalltalk in Argentina. Intent: ------- Implementation for Windows API calls compatible with Visual Smalltalk (3.1x) extensible to other API mechanisms like SOM (under OS2), OLE and Dolphin Smalltalk API. An external library is seen as a subclass of DynamicLinkLibrary (for API calls) under category: 'Squeak External Calls'. If you want to connect a new library you must evaluate: Dynalink32 variableByteSubclass: #MyDLL instanceVariableNames: '' classVariableNames: '' poolDictionaries: '' category: 'Vsw310 - My DLLs' and implement the class method #fileName like: fileName "Answer the receiver's file name." ^'My.dll' To load the library you can inspect the result of evaluating MyDLL current inspect "The message #current returns an open instance of aDynamicLinkLibrary and it is treated as the default library; then when another object evaluates 'MyDLL current' the same object will be returned. If you want to open a new (fresh) instance you must send #open " To free aDynamicLinkLibrary you MUST send #release To implement an API call you must write a method. Each function provided by the DLL must be implemented as a Smalltalk method. API methods are methods like primitive methods but it has the <api: ...> descriptor (like <primitive:...> API methods must provide: 1.- the API function name 2.- the argument types 3.- the result type See methods of KernelDLL UserDLL GDIDLL as examples. API function name can be a symbol or a string matching to a function declared by the DLL. Argument types are the argument types (that can be obtained from the .H file) and must match the types defined by the class apiInfo (see DynamicLinkLibrary>>#apiInfo). Result type must be a valid API result defined by ApiInfo. Example: beep: frequency for: duration <api: Beep ulong ulong boolean> ^self invalidArgument Defines an API function named 'Beep' that can be declared as BOOL Beep (int frecuency, int duration) The #invalidArgument method is defined to validate posible API failure conditions. How to start: ------------- 0.- Decompress the ZIP file in a directory (al decompressed source files must be in the same directory). 1.- Start your favourite (1.23) image with the virtual machine (sq.exe) provided in this package. 2.- FileIn the file 'API FileMeIn.txt' (answer NO to re-definitions) 3.- Evaluate testing the expressions with printIt (or DoIt). Other topics of interest: ------------------------- "To build a new virtual machine source file evaluate this expressions." FileDirectory default deleteFileNamed: 'Interp.c'. Interpreter translate: 'Interp.c' doInlining: true. Limitations: ------------ 1.- The framework if partially implemented and only supports API calls. 2.- You must initialize the framework at image startUp (prior to do an API call) evaluating the expression DynamicLinkLibrary startUp. 3.- Currently the maximum of 20 arguments can be used in an API call. File List: ---------- sq.exe Virtual machine with API calls API FileMeIn.txt Installer file. Readme.txt This file. API Test Script.st Test scripts file. Squeak External Calls.st Full source file. (will be fragmented in the future) Vsw310 Compatibility.st Boot source file. -------------------------------------------end of readme--- Ale. Alejandro F. Reimondo Feel free to visit Smalltalk User Group of Argentina (SUGAR) at http://www.sugarWeb.com

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Re: On the security question... (wrong!)
by Christopher Oliver 12 Jan '98

12 Jan '98

> In a fit of pique I wrote: > > My concern is more along the lines of dumping images that contain > > passwords and session keys. I sit corrected. It doesn't seem that there is a reliable way to assure with a standard image that garbage is removed at dump time. Is there a way within 1.23 of forcing a trace-and-compact that I've not run across yet? -- Christopher Oliver Traverse Communications Systems Coordinator 223 Grandview Pkwy, Suite 108 oliver(a)traverse.com Traverse City, Michigan, 49684 (define magic (lambda (f) (lambda (x) x))) (define (more-magic n) (lambda (f) (lambda (x) (f ((n f) x)))))

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Re: #do: on MethodDictionaries
by Tim Olson 12 Jan '98

12 Jan '98

Alejandro wrote: >MethodDictionaries activates the Dictionary>>#do: method that is >implemented like: > >do: aBlock > super do: [:assoc| aBlock value: assoc value ] > >but... assoc is a CompiledMethod (not an association) and does not >undestand #value > >Is this a bug ? Yes, it looks like the do: protocol was missed, although associationsDo: and keysDo: were reimplemented for MethodDictionary. Those are the obvious enumeration protocol for MethodDictionary -- it is less obvious that do: is useful, which is probably why it was missed. The implementation should look something like: do: aBlock tally = 0 ifTrue: [^ self]. 1 to: self basicSize do: [:i | (self basicAt: i) == nil ifFalse: [aBlock value: (array at: i)]] -- tim

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Re: On the security question...
by Tim Rowledge 12 Jan '98

12 Jan '98

On Sun 11 Jan, Christopher Oliver wrote: > I forgot to ask; does the snapshot primitive write objects which are > not live but not yet garbage collected to the image file? The primitive simply dumps object memory to a file; it's up to the Smalltalk code that does all the concommitant work to make sure it can be done properly. Typically, a garbage collect is done, files are closed, sockets shut down, lights turned out, note left out for the milkan etc just before the snapshot prim is called. An old 'classic' tech support problem is caused by unwary users arrang ing for snapshots to be done by a background process... so the snapshot file has something almost, but not quite, entirely useless in it, since the careful shutdown either doesn't get done or is effectively _un-done_. Bad news when the cu stomer is a major corporation and the person who suggested it is high profile 'expert' :-) tim -- "How many Trinoc does it take to change a lightbulb?" "Why do you want to know about our maintenance schedules? Are you planning to attack us in the dark?" Tim Rowledge: rowledge(a)interval.com (w) +1 (650) 856-7230 (w) tim(a)sumeru.stanford.edu (h) <http://sumeru.stanford.edu/tim>

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Re: On the security question...
by Ian Piumarta 12 Jan '98

12 Jan '98

> I forgot to ask; does the snapshot primitive write objects which are > not live but not yet garbage collected to the image file? No. It does a full GC immediately before writing the image. Ian

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Block ciphers in squeak
by Christopher Oliver 12 Jan '98

12 Jan '98

I'm in the process of trying to cruft up a portable secure terminal for system administration tasks. I'm working with Squeak since it pretty much runs the same no matter which platform I'm working with. Before I bend my back to the task of implementing a block cipher such as Square or Blowfish, I though I'd ask if anyone knows of existing work on this topic. All I found after a protracted session with Deja- News was an article by Smith suggesting implementation in assembler or C, but this defeats the goal of portability. I've already hacked up a PK algorithm that takes about 0.9 sec with a 1024 bit composite on a 133MHz Pentium using Piumarta's 1.23 Squeak. Thus, all I'm seeking is a sound block cipher and perhaps a hash. Regards, -- Christopher Oliver Traverse Communications Systems Coordinator 223 Grandview Pkwy, Suite 108 oliver(a)traverse.com Traverse City, Michigan, 49684 (define magic (lambda (f) (lambda (x) x))) (define (more-magic n) (lambda (f) (lambda (x) (f ((n f) x)))))

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Equality test of Dictionaries
by Alejandro F. Reimondo 11 Jan '98

11 Jan '98

Equality test is implemented in Set as: -------------------------------------------------------- !Set methodsFor: 'testing' stamp: 'afr 1/10/98 17:56'! = aSet (aSet isKindOf: Set) ifFalse: [^ false]. self size = aSet size ifFalse: [^ false]. self do: [:each | (aSet includes: each) ifFalse: [^ false]]. ^ true! ! This causes a great degradation of perfomance when comparing a Set to itself because all elements are traversed. This perfomance cost is evident when using big Pool Dictionaries (that inherits from Set); each time you see a class using a big pool dictionary in a browser it waste a long time (determining poolDict names in Smalltalk #keyAtValue: ). I've solved this problem reimplementing #= as: ------------------------------------------------------------------ !Set methodsFor: 'testing' stamp: 'afr 1/10/98 17:56'! = aSet aSet == self ifTrue: [ ^true ]. "Modified because perfomance is degradated for big Dictionaries (like BIG pool dictionaries). Must be revised to conform X3J20 ANSI Smalltalk specification. (#= in AbstractDictionary conforms to Object protocol) afr 1/10/98 17:41" (aSet isKindOf: Set) ifFalse: [^ false]. self size = aSet size ifFalse: [^ false]. self do: [:each | (aSet includes: each) ifFalse: [^ false]]. ^ true! ! BUT, I don't know if it is the best aproach because X3J20 Specification determines that Dictionary protocol conforms to Object protocol; then equality test must be identity test! Comments on this topic will be appreciated. Ale. Alejandro F. Reimondo Feel free to visit Smalltalk User Group of Argentina (SUGAR) at http://www.sugarWeb.com

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Etiquete for #startUp
by Alejandro F. Reimondo 11 Jan '98

11 Jan '98

What is the recommended mechanism to notify anObject (or aClass) than the image has just startedUp. I need to refresh some objects at system startUp and I don't know how to do it in a clean manner (without base method changes). In Visual Smalltalk when the image is startedUp an event is generated and it notifies all its dependents. How can I doit *clean* in Squeak? thanks. Ale. Alejandro F. Reimondo Feel free to visit Smalltalk User Group of Argentina (SUGAR) at http://www.sugarWeb.com

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