Hi,
Thanks for your answer. I guess I understand now why it is image 3.9 who provides the right answer.
Now... back to that code of yours, it is a serious mess. :) (...)
So... I wonder what the 2.5 image does to end up with a BlockContext, don't have one handy. Perhaps it does some funny stuff if the argument to Compiler is an Array?
Yes, the code was a mess. The same result is obtained by printing the result of:
(Compiler evaluate: #([ Transcript show: 'Some Text' ])) class
image 2.5 --> BlockContext image 3.9 --> Array
I've been playing a little bit more with Squeak, and I found another strange (to me; please, consider that I am still a newbie) thing. In some lectures by Stephane Ducasse there is an example illustrating the difference between literal arrays and arrays created with new:. In particular, adding the following method to class SmallInteger:
m1
| anArray | anArray := #( nil ). (anArray at: 1) isNil ifTrue: [ Transcript show: 'Put 1'; cr. anArray at: 1 put: 1. ] and executing
1 m1
should display the message 'Put 1' only once. And this is how it works... in image 3.9
But if we repeat the experiment in image 3.0, it displays nothing in the Transcript (not even the first execution). Again, I am puzzled by this behavior (I am always assuming that these experiments that behave differently in different Squeak images are standard Smalltalk).
One more thing. Perhaps there is people wondering why someone should worry about the behavior of an old image. The answer is that I am using a stripped version of image 3.0 to play with Squeak on a Jornada 720. More recent complete images are too heavy for the J720 (at least that is my experience; any clue on how to improve that?).
Well, thanks in advance for your answers
Bests
Jordi
El 1/30/07 9:31 AM, "Jordi Delgado" jdelgado@lsi.upc.edu escribió:
The answer is that I am using a stripped version of image 3.0 to play with Squeak on a Jornada 720. More recent complete images are too heavy for the J720
You could try SqueakLight from http://www.squeak.org/Download/
I have a most stripped one, 3.7 derived also
If you do, I wish know any problems.
Edgar
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Hi!
I've been playing a little bit more with Squeak, and I found another strange (to me; please, consider that I am still a newbie) thing. In some lectures by Stephane Ducasse there is an example illustrating the difference between literal arrays and arrays created with new:. In particular, adding the following method to class SmallInteger:
m1
| anArray | anArray := #( nil ). (anArray at: 1) isNil ifTrue: [ Transcript show: 'Put 1'; cr. anArray at: 1 put: 1. ]
and executing
1 m1
should display the message 'Put 1' only once. And this is how it works... in image 3.9
Odd code though. Arrays created using the literal syntax "#( blab bla )" should not be modified - it is very bad style. The Array is created at *compile time*, not on method activation time. This is why it only has nil in it the first time you call #m1.
But if we repeat the experiment in image 3.0, it displays nothing in the Transcript (not even the first execution). Again, I am puzzled by this behavior (I am always assuming that these experiments that behave differently in different Squeak images are standard Smalltalk).
First of all - Squeak is not a "dead" implementation of Smalltalk-80 or ANSI X3J20. It evolves. The recent largest change is of course the addition of Traits in version 3.9.
In this case you are seeing a difference in how literal Arrays are parsed. I don't have a 3.0 image handy but I bet that if you do an "inspect it" on:
#( nil )
...you will seen an instance of Array with a Symbol in it, *NOT* nil. The Symbol #nil is not the same thing as the object referenced by nil (the sole instance of class UndefinedObject). :)
I have a recollection that the parsing of literal Arrays was changed relatively recently, perhaps it was in 3.9 even (or 3.8), so that the special case of "nil" was parsed into a reference to the object nil, and not parsed into a Symbol. I also vaguely recall that this created lots of interesting problems in old code - but I think it was reasonably worked out.
One more thing. Perhaps there is people wondering why someone should worry about the behavior of an old image. The answer is that I am using a stripped version of image 3.0 to play with Squeak on a Jornada 720. More recent complete images are too heavy for the J720 (at least that is my experience; any clue on how to improve that?).
Check with Aaron Reichow - the Squeak-on-PDAs-expert. :)
regards, Göran
Hi Jordi,
you could try " Transcript show: 'Put 1'; cr; endEntry " without anything around it. This should guarantee that something is send to Transcript *and* displayed (#endEntry forces to display things which are as yet not displayed).
It is perhaps so that older Squeak does not do #endEntry when you just use #show: (as it was the case with Squeak's anchestors).
If #endEntry doesn't help then replace it by #halt to get an idea if your code is really executed.
HTH.
/Klaus
On Tue, 30 Jan 2007 13:31:50 +0100, Jordi wrote:
Hi,
Thanks for your answer. I guess I understand now why it is image 3.9 who provides the right answer.
Now... back to that code of yours, it is a serious mess. :) (...)
So... I wonder what the 2.5 image does to end up with a BlockContext, don't have one handy. Perhaps it does some funny stuff if the argument to Compiler is an Array?
Yes, the code was a mess. The same result is obtained by printing the result of:
(Compiler evaluate: #([ Transcript show: 'Some Text' ])) class
image 2.5 --> BlockContext image 3.9 --> Array
I've been playing a little bit more with Squeak, and I found another strange (to me; please, consider that I am still a newbie) thing. In some lectures by Stephane Ducasse there is an example illustrating the difference between literal arrays and arrays created with new:. In particular, adding the following method to class SmallInteger:
m1
| anArray | anArray := #( nil ). (anArray at: 1) isNil ifTrue: [ Transcript show: 'Put 1'; cr. anArray at: 1 put: 1. ] and executing
1 m1
should display the message 'Put 1' only once. And this is how it works... in image 3.9
But if we repeat the experiment in image 3.0, it displays nothing in the Transcript (not even the first execution). Again, I am puzzled by this behavior (I am always assuming that these experiments that behave differently in different Squeak images are standard Smalltalk).
One more thing. Perhaps there is people wondering why someone should worry about the behavior of an old image. The answer is that I am using a stripped version of image 3.0 to play with Squeak on a Jornada 720. More recent complete images are too heavy for the J720 (at least that is my experience; any clue on how to improve that?).
Well, thanks in advance for your answers
Bests
Jordi
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Edgar J. De Cleene -
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