re-learning smalltalk

Hi,

I am trying smalltalk once again after 5/6 years -- a language hard to say goodbye!

I installed vw7.5nc and tried the tutorial http://www.cincomsmalltalk.com/tutorials/version7/tutorial1/weblogstats9.htm

I tried the following code from the above URL:

|stream line bag xFound|
bag := Bag new.
stream := 'ws000101.log' asFilename readStream.
[ stream atEnd ] whileFalse: [
  line := stream upTo: Character cr.
  line := line copyFrom: 50 to: line size.
  line := line copyFrom: (line indexOf: $/) to: line size.
  line := line copyUpTo: $,.
  xFound := line findString: '.asp' startingAt: 1.
  xFound > 0
  ifTrue:[ bag add: line. ]. ].
stream close.
bag inspect.

In the above,

 line := line copyFrom: 50 to: line size.
  line := line copyFrom: (line indexOf: $/) to: line size.
  line := line copyUpTo: $,.

is resulting "UndefinedObject>>unboundMethod" exception.  The above code without While loop works fine. Can somebody explains what is happening?

Thanks.

With regards,
Damar

Hi Damar,

First let me welcome back in Smalltalk wonderland :)

I just did that example and also got an error: This message needs a
positive integer argument. Here is a "diary" of my dealing with that
problem and this can help you to "get back into" debugging such problems:

1. Debugging shows that line size = 0 in:

        line := line copyFrom: 50 to: line size

    which is obviously wrong.

2. What is wrong with that line? Why it is empty?

Let me inspect a stream collection and specially its current position:
124. On that position we have Character lf (I'm on Linux). Hmm, here can
be a problem. The example code seems to expect cr as line-end but we
have a crlf combination.

3. Visualworks internaly use just cr for line-end, so we need to read a
file and make appropriate transformation. Usually it suffices to send a
read stream a message #lineEndTransparent :

stream := 'ws000101.log' asFilename readStream lineEndTransparent.

4. Let me rerun an example: again an error, but now on stream position
3536, again with lf! So above method didn' solve a problem? Let me
inspect position 124 again: in the middle of text. What about end of
line? still crlf.

5. Well let we be more specific about line end convention, let we use a
method #lineEndCRLF :

stream := 'ws000101.log' asFilename readStream lineEndCRLF.

Good, now we got a bag of urls as expected.


I hope that above debugging scenario will help you in a future too.

Best regards
Janko


Damar Thapa wrote:
--
Janko Mivšek
AIDA/Web
Smalltalk Web Application Server
http://www.aidaweb.si