Beginners July 2008

beginners@lists.squeakfoundation.org

62 participants
72 discussions

Debuggig or answering my own questions
by Edgar J. De Cleene 31 Jul '08

31 Jul '08

I was asking about how to trace some until top procedure Now I wish share my solution to all, just in case some need do know. (HttpService on: 8080 named: 'Debug1') onRequestDo: [ :httpRequest | HttpResponse fromString: 'SqueakRos Greet You'. self dpsTraceUntilRoot: httpRequest ]; start 'From SqueakLight|II of 31 May 2008 [latest update: #7198] on 31 July 2008 at 6:41:26 am'! !Object methodsFor: 'error handling' stamp: 'edc 7/31/2008 06:39'! dpsTraceUntilRoot: anObject | reportString context count | Transcript open. reportString := (anObject respondsTo: #asString) ifTrue: [anObject asString] ifFalse: [anObject printString]. (Smalltalk at: #Decompiler ifAbsent: [nil]) ifNil: [Transcript cr; show: reportString] ifNotNil: [context := thisContext. count := 1. [Transcript cr. Transcript show: count printString, ': '. reportString notNil ifTrue: [Transcript show: context home class name , '/' , context sender selector, ' (' , reportString , ')'. context := context sender. reportString := nil] ifFalse: [(context notNil and: [(context := context sender) notNil]) ifTrue: [Transcript show: context receiver class name , '/' , context selector. count := count + 1]]. context sender notNil]whileTrue]! ! I try to cook a micro image using Alejandro Reimondo technique into SqueakLightII. The goal is the micro image could greet to Firefox web browser and quit. I afraid as size is 76 k on first try, can't be send here as attached because is too big :=) So thanks to all and wait Fenix ponga un Huevo (the Fenix laid an Egg). Edgar

1 0

htmlcssparser package/discovering size of objects
by Marcin Tustin 30 Jul '08

30 Jul '08

Hello everyone, a slightly involved and multi-part question: I'm using the package at http://www.squeaksource.com/htmlcssparser (HTML/CSS Parser, or "the parser") to scrape multiple pages (in fact about two or three a day, and about a thousand existing pages), so I can extract parts of them to put into an rss feed. If I let the root object for a parse (the Validator's dom object) be garbage collected, none of the rest of the parse tree really works (because then other objects only referred to weakly get collected, AFAICT). So, my first question is whether there's a way to assess what kind of memory overhead there would be for keeping each of these objects hanging around indefinitely. My second is whether anyone has any advice for another way to do it - by using a different parser, or by copying the data into a different structure somehow, or something else.

2 1

What does the -> symbol mean?
by Andy Burnett 30 Jul '08

30 Jul '08

> > <<It's actually a binary (one-argument, infix) method, like +, =, or ==; > it's the - and > characters put together rather than being a > specialized glyph like the left arrow was. It creates an Association, > which is a key-value pair used in things like Dictionaries. > > If I remember correctly, any characters which can be used for binary > methods can be strung together to make other binary methods - > sometimes you'll see these turn up in specialized contexts. For > example, there's also ==>, on Booleans, for implication ("a implies b"). > > Ben Schroeder>> Thanks Ben, that makes a lot of sense. It's similar to how 1 @ 2 will return a point. And, of course, after reading your answer I realised that what I should have done is used the method finder to look up ->. I just haven't quite got it into my head that there are only objects and messages, and therefore if something isn't an object, it has to be a message! :-) Cheers AB

1 0

What does the -> symbol mean?
by Andy Burnett 30 Jul '08

30 Jul '08

I can't find it in my introductory books. The content was: self entries add: aString -> aBlock Is it a bit like the underscore character being the same as := ? thanks AB

3 2

Re: [Newbies] Re: Linked list structure?
by Marcin Tustin 29 Jul '08

29 Jul '08

Yes. I first tried to subclass LinkedList, but I had some trouble with funny behaviours turning up in do:, although I suppose that has probably been eliminated here by using not trying to use super do: as I did. (By "funny" I mean ending up calling element on the result of element). On Mon, Jul 28, 2008 at 10:04 PM, nicolas cellier <ncellier(a)ifrance.com>wrote: > Marcin Tustin a écrit : > >> I am aware of LinkedList. It does not meet the criterion of accepting >> items whatever their protocol. >> >> > You are right, current implementation of LinkedList is very specialized and > restricted. > Creating Links transparently would be a plus. > Hey, we can use a Dictionary without being aware of Association! > > I am not aware of such implementation, but wouldn't be surprised it already > exists. Rather than a long research, it is easier to DIY. > > I provide an untested quick first implementation as an example. > This implementation uses already existing StackLink transparently. > This could of course be completed with addLink: removeLink: etc... > > Reading code enabled me finding http://bugs.squeak.org/view.php?id=7136 > > So a prerequisite is: > Installer mantis ensureFix: 7136. > > Last, as all code I publicly released in Squeak until now, consider this > code as MIT. Change it, republish it, sell it or throw it away at will. > > Cheers > > Nicolas > > 'From Squeak3.10beta of 22 July 2007 [latest update: #7159] on 28 July 2008 > at 10:48:46 pm'! > LinkedList subclass: #TransparentLinkedList > instanceVariableNames: '' > classVariableNames: '' > poolDictionaries: '' > category: 'Collections-Sequenceable'! > !TransparentLinkedList commentStamp: 'nice 7/28/2008 21:47' prior: 0! > I represent a collection of links, which are containers for other objects. > Using the message sequence addFirst:/removeLast causes the receiver to > behave as a stack; using addLast:/removeFirst causes the receiver to behave > as a queue. > > Unlike super, users won't see the Link objects, like users of Dictionary do > not need to know about Association. > That's why i am called TransparentLinkedList.! > > > !TransparentLinkedList methodsFor: 'adding' stamp: 'nice 7/28/2008 22:47'! > add: anObject after: otherObject > "Add anObject after otherObject in the list. Answer anObject. > If otherObject is not in the list, then raise an error." > > | otherLink | > otherLink := self findLinkFor: otherObject ifAbsent: [^self error: > 'otherObject is not in this list']. > super add: (StackLink with: anObject) after: otherLink. > ^anObject! ! > > !TransparentLinkedList methodsFor: 'adding' stamp: 'nice 7/28/2008 22:47'! > add: anObject before: otherObject > "Add anObject after otherObject in the list. Answer anObject. > If otherObject is not in the list, then raise an error." > > | otherLink | > otherLink := self findLinkFor: otherObject ifAbsent: [^self error: > 'otherObject is not in this list']. > super add: (StackLink with: anObject) before: otherLink. > ^anObject! ! > > !TransparentLinkedList methodsFor: 'adding' stamp: 'nice 7/28/2008 21:54'! > addFirst: anObject > "Add anObject to the beginning of the receiver's list. Answer > anObject." > > super addFirst: (StackLink with: anObject). > ^anObject! ! > > !TransparentLinkedList methodsFor: 'adding' stamp: 'nice 7/28/2008 21:53'! > addLast: anObject > "Add anObject to the end of the receiver's list. Answer anObject." > > super addLast: (StackLink with: anObject). > ^anObject! ! > > > !TransparentLinkedList methodsFor: 'removing' stamp: 'nice 7/28/2008 > 22:11'! > remove: anObject ifAbsent: aBlock > "Remove anObject from the receiver. If it is not there, answer the > result of > evaluating aBlock." > > | aLink | > aLink := self findLinkFor: anObject ifAbsent: [^aBlock value]. > super remove: aLink ifAbsent: aBlock. > ^anObject ! ! > > !TransparentLinkedList methodsFor: 'removing' stamp: 'nice 7/28/2008 > 21:55'! > removeFirst > "Remove the first element and answer it. If the receiver is empty, > create > an error notification." > > ^super removeFirst element! ! > > !TransparentLinkedList methodsFor: 'removing' stamp: 'nice 7/28/2008 > 21:55'! > removeLast > "Remove the first element and answer it. If the receiver is empty, > create > an error notification." > > ^super removeLast element! ! > > > !TransparentLinkedList methodsFor: 'enumerating' stamp: 'nice 7/28/2008 > 22:12'! > do: aBlock > > self linkDo: [:aLink | aBlock value: aLink element]! ! > > !TransparentLinkedList methodsFor: 'enumerating' stamp: 'nice 7/28/2008 > 22:10'! > findLinkFor: anObject ifAbsent: aBlock > self linkDo: [:aLink | aLink element = anObject ifTrue: [^aLink]]. > ^aBlock value! ! > > !TransparentLinkedList methodsFor: 'enumerating' stamp: 'nice 7/28/2008 > 22:15'! > linkDo: aBlock > "this could be ^super do: but I dislike sending super with a > different message selector" > > | aLink | > aLink := firstLink. > [aLink == nil] whileFalse: > [aBlock value: aLink. > aLink := aLink nextLink]! ! > > !TransparentLinkedList methodsFor: 'enumerating' stamp: 'nice 7/28/2008 > 21:57'! > reverseDo: aBlock > > super reverseDo: [:aLink | aBlock value: aLink element]! ! > > !TransparentLinkedList methodsFor: 'enumerating' stamp: 'nice 7/28/2008 > 21:58'! > species > > ^ self class! ! > > > !TransparentLinkedList methodsFor: 'accessing' stamp: 'nice 7/28/2008 > 21:58'! > first > ^super first element! ! > > !TransparentLinkedList methodsFor: 'accessing' stamp: 'nice 7/28/2008 > 21:58'! > last > ^super last element! ! > > _______________________________________________ > Beginners mailing list > Beginners(a)lists.squeakfoundation.org > http://lists.squeakfoundation.org/mailman/listinfo/beginners > >

1 0

Re: [Newbies] Linked list structure?
by Marcin Tustin 28 Jul '08

28 Jul '08

I am aware of LinkedList. It does not meet the criterion of accepting items whatever their protocol. On Mon, Jul 28, 2008 at 7:12 AM, David T. Lewis <lewis(a)mail.msen.com> wrote: > On Sun, Jul 27, 2008 at 10:27:08PM -0400, Marcin Tustin wrote: > > Is there - either as standard, or freely downloadable - a datastructure > that > > is ordered, has constant-time appends of items, requires no particular > > protocol of the items stored, and can be iterated over (without > allocating a > > new structure) starting with the first item added, proceeding to the next > > item added? I.e. has the characteristics of a linked list structure in > most > > other datastructure libraries? > > Have a look at class LinkedList. This is one of the "kernel" classes in > Squeak > and is used by ProcessorScheduler to manage processes (the "threads" within > a Squeak image, instances of class Process). A Squeak Process is > implemented > as a subclass of Link, and it is kept as an entry in the linked list. Try > evaluating "Processor explore" to look at the singleton instance of > ProcessorScheduler > that manages these linked lists. > > Dave > > _______________________________________________ > Beginners mailing list > Beginners(a)lists.squeakfoundation.org > http://lists.squeakfoundation.org/mailman/listinfo/beginners >

2 1

Invoking MIDIInputParser
by George Kopeczky 28 Jul '08

28 Jul '08

I'm a Squeak newbie with nearly zero programming experience, brought here by a search after a tool that will let me capture, view as hex (and hopefully, save) a rare type of MIDI message (Active Sensing) which is unrecorded by every MIDI sequencing application I tried. The MIDIInputParser object seems to be the ticket, but how do I invoke it? Whether I choose "Object Catalog" from the menu, or just click the Objects tab in Squeak's playfield, there is no trace of MIDIInputParser (or its Sound-Score Category) between the resources offered. I looked at the Squeak tutorials list, I haven't seen a MIDI-related one. I could use a little orientation on how to proceed... thank you in advance George

3 2

Linked list structure?
by Marcin Tustin 28 Jul '08

28 Jul '08

Is there - either as standard, or freely downloadable - a datastructure that is ordered, has constant-time appends of items, requires no particular protocol of the items stored, and can be iterated over (without allocating a new structure) starting with the first item added, proceeding to the next item added? I.e. has the characteristics of a linked list structure in most other datastructure libraries?

3 2

Re: [Newbies] Linked list structure?
by Marcin Tustin 28 Jul '08

28 Jul '08

Technically, that would have amortised constant time adds, but yes, that's good enough for me. On Sun, Jul 27, 2008 at 10:57 PM, Michael van der Gulik <mikevdg(a)gmail.com>wrote: > > > On Mon, Jul 28, 2008 at 2:27 PM, Marcin Tustin <mm3(a)zepler.net> wrote: > >> Is there - either as standard, or freely downloadable - a datastructure >> that is ordered, has constant-time appends of items, requires no particular >> protocol of the items stored, and can be iterated over (without allocating a >> new structure) starting with the first item added, proceeding to the next >> item added? I.e. has the characteristics of a linked list structure in most >> other datastructure libraries? >> > > > I believe it's called an OrderedCollection, and it's in every Smalltalk > image you'll find(*). > > I recommend reading through Chapter 9 of Squeak by Example (under > "Documentation" on http://www.squeak.org/). It give a good explanation of > Squeak collections and how to use them. > > Gulik. > > (*) Perhaps except for Craig Latta's 1337-byte image. > > -- > http://people.squeakfoundation.org/person/mikevdg > http://gulik.pbwiki.com/ > > _______________________________________________ > Beginners mailing list > Beginners(a)lists.squeakfoundation.org > http://lists.squeakfoundation.org/mailman/listinfo/beginners > >

1 0

Morphic, Tweak and Plopp
by Andy Burnett 28 Jul '08

28 Jul '08

>> I have just started playing with Plopp (very impressive). The >> reason I downloaded it was to see the sort of interfaces that people >> could build in Squeak. What I am wondering is whether the UI is >> built on top of Morphic, or whether it is completely different. >> Does anyone know? >The 2D UI is Tweak, the 3D rendering Croquet. >I'm pretty sure you could do the same kind of UI in Morphic though. >Just hire great designers ;) >- Bert - Ah yes, with a good designer - and enough time - anything is possible :-) However, you response raises other questions in my mind. In my beginner's mind, Squeak and Morphic are all wrapped up as one thing. Clearly though, that isn't the case. So, are there any rules of thumb about when one would build an application using the Morphic classes and when to use something else? Also, what might the 'something elses' be? For example, it seems as though both Plopp and Sophie use Tweak and Croquet (if I understand the email thread correctly). So, does that imply that Morphic is great of e-toys etc, but not for stand alone applications? I like being able to play with morphs, but I am trying to build some applications that are more like Sophie etc. What do the assembled experts think? Also, do you think of web browsers (via Seaside etc) as just another Squeak rendering model, i.e. should that be added to my list of potential UI libraries, or is it a very different development process? Cheers AB

2 1

2024

2023

2022

2021

2020

2019

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

Beginners July 2008