Beginners June 2006

beginners@lists.squeakfoundation.org

47 participants
50 discussions

linux squeak startup
by cdrick 08 Jul '06

08 Jul '06

Hi all :) do you know how to make an init.d script to start squeak each time a linux server starts... It's for seaside. For now I use a command line squeak -nodisplay myImage.image but when I close the shell, squeak stops too Thanks for all :) Cédrick

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variableWordSubclass:
by Joaquin Sitte 03 Jul '06

03 Jul '06

Hi, Please can someone explain the behaviour described below? I wish to create a subclass of FloatArray for a dynamic system simulation. When creating the class with #subclass: the method is automatically changed to #variableWordSubclass: as follows FloatArray variableWordSubclass: #DynamicVariable That is fine. But when I wish to create an instance dv2 _ DynamicVariable new: 2 I get an error telling me that #new: is not understood. However #new: is understood by the superclass #FloatArray. Why? And, by the way, the method #variableWordSubclass cannot be found with Method Finder. Why? Many thanks in advance. Joaquin Dr. Joaquin Sitte, Associate Professor. School of Software Engineering and Data Communication Faculty of Information Technology Queensland University of Technology GPO Box 2434, Brisbane, Q 4001 Australia Phone +61 7 3864 2755 Fax +61 7 3864 1801 e-mail: j.sitte(a)qut.edu.au homepage <http://www.fit.qut.edu.au/~sitte> http://www.fit.qut.edu.au/~sitte

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xml file query and object mapping
by cdrick 30 Jun '06

30 Jun '06

Hi all I've got xml files that I receive from Meteo France (weather forecast) that I have to query and map to some objects I've tried several stuff like parsing the file, selecting only some elements, displaying it with a WATree but I'm a bit stuck as none results I got are good enough. The structure is like behind: <?xml version="1.0" encoding="UTF-8" ?>... <donnees> <dates>...</dates> <prevision> <prev num="1"> // a prev concern a zone for 3 hours - there are 18 prev for a given zone <ZONE>6403</ZONE> <VALIDITE>200606292000</VALIDITE> <JJ>20060629</JJ> <HH>2000</HH> <T>24</T> <PICTO>P6</PICTO> <DD>315</DD> <FF>10</FF> <RAF></RAF> <ISO_ZERO>4100</ISO_ZERO> <LIMIT_PLUIE_NEIGE></LIMIT_PLUIE_NEIGE> <W1>0</W1> <W2></W2> <NEBUL_TOT>3</NEBUL_TOT> <BASE_NUAGE></BASE_NUAGE> <SOMMET_NUAGE></SOMMET_NUAGE> <FF1500M>5</FF1500M> <FF3000M>25</FF3000M> <RR6>0.4</RR6> <W3></W3> <EPAIS_NEIGE></EPAIS_NEIGE> <VIGILANCE></VIGILANCE></prev> .... around 450 prev (18 for each ZONE) <prevQ num="1"> // this are prevision for the whole day - 4 prevQ in each file for a given zone <ZONE>3107</ZONE> <VALIDITE>200606290000</VALIDITE> <JJ>20060629</JJ> <TN>15</TN> <TX>26</TX> <RR24>1.0</RR24> <UN>60</UN> <UX>100</UX></prevQ> ... </prevision> </donnees> What I need to do is quering the file according to the some attribute (ZONE, VALIDITE, JJ and HH) so as to get the different value that characterize the weather forecast. The only thing I can do is selecting nodes accoring to one parameter, for instance all prevQ element of zone 6504 (using Xpath). | xml document path results | xml := (StandardFileStream readOnlyFileNamed: 'ressources/MF/backup/sympo0805200617h00.xml') contents. document := XMLDOMParser parseDocumentFrom: xml readStream. path := XPath for: 'prevision/prev'. results := path in: document. ^ results select: [:xmlElem | (xmlElem elementAt: #ZONE) contents first string = '6504'] I'm a bit lost now. Is it possible to map to objects ? do I need to work directly on xml file by xsl transformation ? I don't really understand how to use a sax parser (I always do a full dom parse that I store in an inst var). Do you have advices, pointers or other good practises that can help me ? Thanks Cédrick

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Re: [Newbies] Tables for WideString?
by Алексей 29 Jun '06

29 Jun '06

Hello, Yoshiki. Thanks for detailed answer. It was in image 3.8 from squeak.org I fix problem by creating accessors to mentioned tables in String and overriding them in WideString. Also some small changes in Character and new class wideCharacterSet. About "variableWordSubclass" and other. I have no words... To create class I send message to it superclass!!! It is beutiful way. I'd understand how it work only after question was posted. Before I thought, that it is a kind of 'keyword' :) Alexei. >> I have problems with WideString. (realy not with WideString, but >> debugger brings me to this class). When I send #beginsWith: message to >> WideString, squeak invokes String>>beginsWith: and this method use >> String>>findSubstring:in:startingAt:matchTable: >> For String matchTables (AsciiOrder CaseInsensitiveOrder >> CaseSensitiveOrder) contains 256 bytes. >> So when invoked 'matchTable at: myWideChar asciiValue + 1' -- i get >> error -- 'subscript is out of bounds'. >> >> How to fix this? >> I must create my own huge tables for wide strings? > > This must be a bug, I think. It is fixed in Squeakland image, but > not incorporated into the mainstream yet. What was the version you > found this? > >> And another question. >> From class definition for WideString >> 'String variableWordSubclass: #WideString' >> What means 'variableWordSubclass' and is it restrict me in some way, >> or I can ignore this? > > There is a concept of the "variable class" in Smalltalk. If you > take an instance of a normal class, its size is fixed (i.e., the > instance has a number of slots that is defined by the "class shape"). > And, each slot are (usually) named, and the name is used to access > them in the user code. > > For a variable class, its instances can have different size. For > example, the instances of Array can be different size, but share the > same behavior provided by the Array class. The slots are index by > numbers. > > A String in Squeak is like an Array. Each (sub-)instance of it can > have different size. A "variable word class" means that a slot of its > instance contains a 32-bit word (non-pointer), and a "variable byte > class" means a slot is 8-bit wide (obviously a non-pointer). > > The restriction? You cannot have a named instance variable in > a non-pointer variable class. > > -- Yoshiki

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What was first: the chicken or the egg?
by 啸然 29 Jun '06

29 Jun '06

In Squeak, what was first: VM or image? It is said the Squeak VM is created by itself, but how to run the first image file? And how to creat the first image file? I wondered whether the VM C source code should be first created? Thanks.

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EmphasizedMenu question
by Thomas Keller 29 Jun '06

29 Jun '06

Greetings, I'm working through http://www.maartensz.org/computing/squeak/Helps/Environment/Workspaces4.htm and * (EmphasizedMenu selections: #('bold' 'plain' 'italic' 'struckout' 'plain' 'nice menu!') emphases: #(bold plain italic struckOut plain bold)) startUp *Gives me the "MessageNotUnderstood" error: doesNotUnderstand: aMessage "Handle the fact that there was an attempt to send the given message to the receiver but the receiver does not understand this message (typically sent from the machine when a message is sent to the receiver and no method is defined for that selector)." "Testing: (3 activeProcess)" (Preferences autoAccessors and: [self tryToDefineVariableAccess: aMessage]) ifTrue: [^ aMessage sentTo: self]. MessageNotUnderstood new message: aMessage; receiver: self; signal. ^ aMessage sentTo: self. Can someone explain what I've done wrong? (currContext := only) -- Tom "Ecrasez l'Infame!" -- Voltaire

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Tables for WideString?
by Алексей 28 Jun '06

28 Jun '06

Hello!!! I have problems with WideString. (realy not with WideString, but debugger brings me to this class). When I send #beginsWith: message to WideString, squeak invokes String>>beginsWith: and this method use String>>findSubstring:in:startingAt:matchTable: For String matchTables (AsciiOrder CaseInsensitiveOrder CaseSensitiveOrder) contains 256 bytes. So when invoked 'matchTable at: myWideChar asciiValue + 1' -- i get error -- 'subscript is out of bounds'. How to fix this? I must create my own huge tables for wide strings? And another question. From class definition for WideString 'String variableWordSubclass: #WideString' What means 'variableWordSubclass' and is it restrict me in some way, or I can ignore this? Thanks. Alex.

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what's the existing projects to save objects?
by trolat.florent 26 Jun '06

26 Jun '06

Hi all, :) I search to save an object (and the objects which possibly composed it) onto a storage medium ("serialization"?). I hope with your great kindness (too much? ) you could give me some ways to explore or some names of projects... Thanks, Flo. Accédez au courrier électronique de La Poste : www.laposte.net 3615 LAPOSTENET (0,34 /mn)

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Re: [Newbies] variableWordSubclass:
by ncellier＠ifrance.com 26 Jun '06

26 Jun '06

Sorry to repost, my webmail interface was using html instead of plain text... To understand a little bit more: When you execute (FloatArray new: 2), you send message #new: to class FloatArray with argument 2. Message #new: is looked up in the receiver class methodDictionary, that is (FloatArray class) here. Note that (FloatArray class) is a an instance of Metaclass: FloatArray class class. which is a kind of Behavior: FloatArray class class superclass superclass. If #new: is not implemented in (FloatArray class), it must be in one of its successive superclasses. FloatArray class allSuperclasses. You get an OrderedCollection(ArrayedCollection class SequenceableCollection class Collection class Object class ProtoObject class Class ClassDescrip tion Behavior Object ProtoObject) What is causing you trouble is that the hierarchy browser is hiding this hierarchy... >From the Browser, FloatArray browseHierarchy. you can only see: FloatArray allSuperclasses. And this one only show you a HierarchyBrowser on Metaclass: FloatArray class browseHierarchy. I remember from a browser showing the whole Metaclass hierarchy once... (was it parcplace st-80 v2.3 ?). Maybe it would help newbies understand better this subtle part of Smalltalk. Hope it helps. Nicolas ________________________________________________________________________ iFRANCE, exprimez-vous ! http://web.ifrance.com

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Re: [Newbies] variableWordSubclass:
by ncellier＠ifrance.com 26 Jun '06

26 Jun '06

To understand a little bit more: When you execute (FloatArray new: 2), you send message #new: to class FloatArray with argument 2. message #new: is looked up in the receiver class methodDictionary, that is (FloatArray class) here. Note that FloatArray class is a an instance of Metaclass, which is a kind of Behavior. FloatArray class class. FloatArray class class superclass superclass. If #new: is not implemented in (FloatArray class), it must be in one of the superclass. FloatArray class allSuperclasses. You got an OrderedCollection(ArrayedCollection class SequenceableCollection class Collection class Object class ProtoObject class Class ClassDescription Behavior Object ProtoObject) What is causing you trouble is that the hierarchy browser is hiding this hierarchy... >From the Browser, FloatArray browseHierarchy you can only see: FloatArray allSuperclasses. And this one only show you a HierarchyBrowser on Metaclass: FloatArray class browseHierarchy. I remember from a browser showing the whole Metaclass hierarchy once (was it parcplace st-80 v2.3 ?). Maybe it would help newbies understand better this subtle part of Smalltalk. Hope it helps. Nicolas ________________________________________________________________________ iFRANCE, exprimez-vous ! http://web.ifrance.com

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Beginners June 2006