Beginners December 2007

beginners@lists.squeakfoundation.org

47 participants
37 discussions

Symbols, my nightmare
by Chris Cunnington 29 Dec '07

29 Dec '07

Me: > I tried this: > > Object respondsTo: asMorph > > I print it, and get: > > Object respondsTo: asMorph false > Ralph Johnson: >It should be "Object respondsTo: #asMorph". But in fact, you can say >"3 respondsTo: #asMorph". The reason that the first works is that >Object is an instance of a subclass of Object. #asMorph is a >message you send to instances, not classes. I've got a question about this exchange, about symbols. Why do we use symbols? What are they for? I know that all class names are symbols. We define them in the template with a hash mark, and then the class name has immediate global scope. We can call it from anywhere. Also, we only need to hash mark when we declare a symbol. I can call the name of a class from anywhere without using the hash mark. I know that sometimes a programmer will use a symbol as an argument. Above, my use of Object calls a variable called asMorph. Ralph Johnson adds the symbol, and now the argument is referring to a method called asMorph. Does that mean people have a choice between a symbol and a block? If I want the selector to call another method, it seems I could write #asMorph or [asMorph]. And why do people on this message board refer to the selectors in question as though they were all symbols? (i.e. #respondsTo:) respondsTo: is a selector, not a symbol. Is that just some kind of convention, because it's not what the code is doing. respondsTo: is a selector, not any symbol... I don't think. The kicker. Ralph Johnson says: "#asMorph is a message you send to instances, not classes". What? AsMorph is a method. A method of the class Object. If I write "Object respondsTo: #asMorph", then I'm saying "Hello, Object, do you happen to have a method called asMorph?". (Object makes this a bit confusing, I think, because you can ask any class if they have method asMorph, and it will be true, because any class can find asMorph by asking Object, which is at the top of the hierarchy.) But what does Ralph Johnson mean that you send #asMorph, a symbol for a method, only to an instance? And not a class? And finally, if you create a symbol for a method, then doesn't that give that symbol global scope, as it did with the defining of a class? And wouldn't that undermine polymorphism? There are more than half a dozen classes that use the method asMorph. I should say, there are nine implemention of asMorph. Each defined in its own way. If a symbol has universal scope, then how does the system chose one of those nine? How do you limit the scope of a symbol? Any help would be greatly appreciated, Chris

4 5

Squeak equivalent for Filename
by Doug Edmunds 23 Dec '07

23 Dec '07

Cincom VisualWorks has this code to read the names of the files in a directory: (Filename named: '.') directoryContents "returns an array of string" What is the equivalent in Squeak? --dae

2 3

Re: Squeak equivalent for Filename
by Doug Edmunds 23 Dec '07

23 Dec '07

Frank Urbach wrote: > > Hi Dae, > > > > to use the FileDirectory you have to use the full pathname on your system e.g. C:\temp. How then do I find out what the full pathname is of the current directory (the equivalent to '.')? -- dae

2 1

FFI, ODBC
by Miron Brezuleanu 21 Dec '07

21 Dec '07

Hello, I'm trying to install the ODBC driver for Squeak and I run into the following issues: 1) when using squeak vm 3.10 (with Ramon Leon's image or the 3.9 image) the FFI is installed without errors from SqueakMap, but when trying to install the ODBC package the image freezes (apparently while downloading). 2) with squeak 3.9 the FFI install fails with a SHA1 error: ------------- Download from original url (http://map.squeak.org/accountbyid/cf58c358-46ee-465e-b6db-2740e9b32a53/file…) failed with this exception: Incorrect SHA checksum of file from orginal URL Trying server cache instead. Download from server cache of FFI 1-3.9 failed with this exception: Incorrect SHA checksum of file from server ------------ 3) squeak vm 3.10 with image 3.10.gamma.7159 also gives the sha1 error when installing FFI. Also, the 7159 image doesn't have the sources file and the image complains about it when starting. Do I really need the sources file (the class browser seem to be able to display method sources) and if yes, where do I find them? OS is XP SP 2. I've searched the mailing list archives but only found the pointer about loading ffi before odbc which led me to the current situation. Many thanks for any pointers/ideas, -- Miron Brezuleanu

2 4

TestFailure: Assertion failed in first practice from Squeak by Example
by Jerome Peace 20 Dec '07

20 Dec '07

[Newbies] TestFailure: Assertion failed in first practice from Squeak by Example Hi Eric, You have and interesting one here. I tried your example in both sq 7159 (3.10 basic) and in damiens sq dev (sqdev7154-07.11.1) i.e the november version based on sq 7154 basic. In both of those images the example worked as the book said it would. So either you have found an obscure bug in an obscure version or have made a typing error in the one you tried. (If it were me I would suspect a typo but then I have always been a creative typer. ;-) Of course the fun thing to do with an error is learn how the debugger works. Open the debugger (from the test runner click on the failed method testShout that will get the pre-debugger. click on debug. select the line with StringTest>>#testShout in it and play with it trying to find a way to pinpoint the exact error. If you are open to what you see, you are bound to learn something that will increase your squeaking skills. Now that's really learning Squeak by Example!* hth, Yours in curiosity and service, --Jerome Peace "There are no wrong answers only interesting results." - Seymour Papert (somewhat folk processed). I learned it while learning Logo. Eric Eisaman eric.eisaman at gmail.com Tue Dec 11 20:38:18 UTC 2007 Hello Jerome, I checked the white space and it was the same. I went and created numerous other String methods basically invoking existing methods and every test run seems to yield a signal failure causing the assertion to fail. I moved from the Cassou Dev Image to the OLPC Etoys Dev Image and made several of my own String methods and respective tests which all ran successfully. I don't know why my coding didn't work in both cases. Thanks for the time. Have a good day. Regards, Eric Eisaman "Scratch yourself into Squeaking." http://scratch.mit.edu/users/eisaman On Dec 12, 2007 4:46 AM, Jerome Peace <peace_the_dreamer at yahoo.com> wrote: > TestFailure: Assertion failed in first practice from > Squeak by Example > > Hi Eric, > > Check your white space. > > There is a difference between 'oh no' and 'oh no '. > While its hard for me to tell if this is your problem > it is a common difficulty. And it will be easy for you > to eliminate it as a possibility. > > Hth. > > Yours incuriosity and service, --Jeorme Peace > > > Eric Eisaman eric.eisaman at gmail.com > Mon Dec 10 21:28:41 UTC 2007 > > > Yes, the shout method is defined in the String object. > > *** > >Eric > > > >On Dec 11, 2007 7:09 AM, stephane ducasse > <stephane.ducasse at free.fr> wrote: > > > >> Hi Eric > >> > >> On 10 déc. 07, at 21:48, Eric Eisaman wrote: > >> > >> > Hell Squeakers, > >> > > >> > At home I went through the first half of the > Squeak by Example > >> > book. The guided practice went without a hitch > however, when I > >> > worked through the first practice of writing a > simple String method > >> > at work, on a different image, I ran into this > problem. Why am I > >> > receiving an 'Assertion failed' message? > >> > > >> > testShout > >> > self assert: ('oh no' shout = 'OH NO!') > >> > > >> > >> where the shout method is defined? > >> In String? > >> > >> > shout > >> > ^ self asUppercase , '!' > >> > > >> > TestFailure: Assertion failed > >> > > >> > Regards, > >> > > >> > Eric Eisaman > *** ____________________________________________________________________________________ Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs

2 1

Request for Review
by pascal.vollmer＠nexgo.de 20 Dec '07

20 Dec '07

Hi, I just uploaded a new version of a SqueakSource project named "Analog Clock tutorial". Since I am rather new to Squeak and since this is meant to be used later on in a programming course in school I'd like to ask if someone could have a look at it. 1. AnalogClock is much like the WatchMorph. The only difference being that AnalogClock is composed of submorphs whereas WatchMorph draws its components itself. The main challenge for me was to get the submorphs adapt to changed position or size of their owner. I can see that my solution works but I feel it is rather ugly. 2. AnalogClock is also able to view upcoming events which stem from an ical-calendar. Toggle this feature in the halo-menu and/or run the tests in order to see. You will need the package 'ical' to run AnalogClock. Find detailed information in the AnalogClock-class. Regards Pascal Pascal Vollmer Email: pascal.vollmer(a)ieee.org Viel oder wenig? Schnell oder langsam? Unbegrenzt surfen + telefonieren ohne Zeit- und Volumenbegrenzung? DAS TOP ANGEBOT FÜR ALLE NEUEINSTEIGER Jetzt bei Arcor: günstig und schnell mit DSL - das All-Inclusive-Paket für clevere Doppel-Sparer, nur 29,95 Euro inkl. DSL- und ISDN-Grundgebühr! http://www.arcor.de/rd/emf-dsl-2

1 0

Exporting Object Memory
by Chris Cunnington 18 Dec '07

18 Dec '07

If I had data in object memory, because I've saved answers from a user into objects, then can I file out that information? If I had to send it to somebody as an csv file, how could I do that easily? I know if I could find an object with the inspector I could print data in the Transcript and cut and paste it into another file, but is there another way? It seems to me that filing out gives you the application, but what if I wanted information that had been entered by the users, the end user data? Chris

5 5

FUN Squeak wish a home for download
by Edgar J. De Cleene 16 Dec '07

16 Dec '07

I send again the Date: Fri, 07 Dec 2007 08:27:34 -0300 mail, links are not actualized. Cheers > 3ShortTangos folder contains > Amablemente.mp3 > Bajo Belgrano.mp3 > Destellos.mp3 > FUNSqueak3.10.1beta.7155.changes > FUNSqueak3.10.1beta.7155.image > > And is packed this way for quick start of SqueakAmp, when user choose his own > music, takes some tiiiiiimeeeeee. > > Into the FunSqueak, you find > Shout > Fabrik > MorphicWrappers > MathMorphs > SendTreeExplorer > Tracing Messages Browser > DebugReport > Network-IRC > Scheduler > ToothPick > Rompecabezas > MoviesFor3dot10 > SqueakAmp > LogicCircus > Connectors > Keymapping > BabySRE > > And some of Jerome, without his knowledge > > I put in http://ftp.squeak.org/3.10alpha/3ShortTangos.zip as I don't have > access to other dir. > > Ken, Brad, could move to appropriate and send notice to community ? > > Edgar People. I actualize FunSqueak, delete 3ShortTangos.zip and now I put http://ftp.squeak.org/3.10alpha/FunSqueak3.10alpha.1.zip To previous list, I add Squeak 3D, RefactoringBrowser, and FreeType. I follow Jerome suggestion to name alpha and treat as derivative of 7159 base image. It's the image I take to Smalltalks 2007 (Buenos Aires) and if any of you wish I say some to people , let me know. Please actualize info and links. Edgar P.S No computer was harmed in the made of this image :=)

2 1

World when: #aboutToEnterWorld send:to:
by Doug Edmunds 15 Dec '07

15 Dec '07

I was trying a tutorial at http://coweb.cc.gatech.edu/cs2340/2200 I ran doIt on this code in a workspace of a project World when: #aboutToEnterWorld send: start to: Demo1. (after creating the Demo1 class and the class method start. Basically, all it does is open a Transcript and write a line or two of text. It works every time I open that project. My primary question is where is the result of the doIt being stored? I would like to be able to change it, disable it, remove it, etc. What tool do I use to find this line of code in the image? How is it that sending code like this one time can cause it to run every time the project gets opened? - dae

2 3

Somthing weird in Set
by Hilaire Fernandes 14 Dec '07

14 Dec '07

How can the following happen ? theSet includes: theOnject -> false theSet asArray includes: theObject -> true previous sent messages to theSet were add: remove:ifAbsent: The Set>>ScanFor: looks strange. Hilaire

2 2

2024

2023

2022

2021

2020

2019

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

Beginners December 2007