News for UCLA Computer Science 131, Fall 2003

2003-11-24

This week only, Paul's office hour tomorrow (11-25) has been moved to Wednesday (11-26) at 09:00.

2003-11-18

There's been some confusion about how a Python program is invoked from the Unix shell (or other top-level environment). The usual tradition is to have code something like the following in your .py file.
```
import sys

# Define a whole bunch of stuff here, including a "run" method.
# (Obviously you can substitute your own name for "run".)

def main ():
    args = sys.argv[1:]
    exit_status = run (args)
    sys.exit (exit_status)

if __name__ == '__main__':
    main ()
```
The if __name__ == '__main__' test causes the resulting code to be executed only if you are running at the top level, not if you merely import the .py file.
The port number base for Project 2 has been changed from 12000 to 14000, to avoid a collision with Computer Science 118. That is, your web server should use port number 14000 + (N mod 424), where N is your student ID.
Project 2 is available. It is due Monday, December 1; late submissions will not be accepted after Friday, December 5. Note that the first (optional) sub-deadline is this Friday at noon.

2003-11-11

Homework 4 is available.

2003-11-10

Reminder: tomorrow is Veteran's Day; there is no class. Instead of Tuesday, Paul will have an office hour on Thursday, 2003-11-13, at 11:00.
Midterm answers are available; look under the midterm subdirectory of the class web page.

2003-11-08

The source for Homework 3 has been corrected as follows, so that your crawlers don't find the valid RURLs http://www.cs.ucla. and http://10.0.0.0 when applied to the Homework 3 web page. This patch does not affect the visual appearance of the Homework 3 web page. This patch is in GNU diff unified format.

--- hw3.html	2003/11/07 07:57:20	1.5
+++ hw3.html	2003/11/09 07:55:50	1.6
@@ -220,8 +220,8 @@ $ #
 $ # The following test cases were added on 2003-11-06.
 $ #
-$ java GetRURLs http://www.cs.ucla.0rg/index.html; echo $?
+$ java GetRURLs http<samp>:</samp>//www.cs.ucla.0rg/index.html; echo $?
 GetRURLs: error: root is not an RURL
 1
-$ java GetRURLs http://10.0.0.0.0/index.html; echo $?
+$ java GetRURLs http<samp>:</samp>//10.0.0.0.0/index.html; echo $?
 GetRURLs: error: root is not an RURL
 1

2003-11-06

In the class resources, an ebook version of Python in a Nutshell has been added, and the reference to the Twisted documentation has been upgraded from version 1.0.7 to 1.1.0.
Several test cases have been added to Homework 3. Look for the the date 2003-11-06 in the text, and see Appendix A of Internet RFC 2396 for details about what exactly is allowed in a URI. Also, the two RURLs http://www.cs.ucla.edu/classes/winter03/cs131/midterm/2a.txt and http://www.cs.ucla.edu/classes/winter03/cs131/midterm/2q.txt have been added to the Homework 3 web page in an HTML comment; your program should find them.

2003-11-03

Homework 3 is available.

2003-10-23

A solution and the test cases used for grading have been appended to Homework 1.
The midterm next week will cover all the material covered in lecture and discussion sections, along with Homeworks 1 and 2, Project 1, and Sebesta §§1-3.3, 15, 16.
Winter 2003's midterms and answers are available. However, that quarter we covered topics in a different order, and used a different language (m4 rather than Python). Therefore, not all of the questions and answers will be directly applicable for studying for the midterm this quarter, and some of this quarter's pre-midterm topics (notably Prolog) were not covered by the old midterms. Also, an earlier edition of Sebesta was used, so the page and section numbers might not match your copy of Sebesta.

2003-10-22

Homework 2 is available; it is due 11-02.
Dr. Eggert will have an extra office hour today from 12:00-13:00.

2003-10-21

A student tested the Project 1 test cases and found some bugs, which have been corrected as follows.

(pmatch-list-list '()) is supposed to return #f, not true. A new example, (pmatch-list-list '(())) has been added that does return true.
Similarly, (pmatch-list-list '((a) (a))) is supposed to return #f, not true. A new example, (pmatch-list-list '((a))) has been added that does return true.
quote-expr has been changed from (list quote obj) to (list 'quote obj).
Three instances of + in the test fragments have been changed to modulo.

2003-10-20

The due date for Homework 2 has been changed to October 27.
The due date for Project 1 has been extended one last time, to Wednesday.
Project 1 has some more examples; look for the string "Some more examples."

2003-10-15

A class discussion board is available.
Project 1 has been corrected as follows.
- The due date has been pushed back to Monday. (The due date for Homework 2 has therefore been tentatively pushed back to next Saturday.)
- An is pattern is not allowed to appear as one of the first N immediate subpatterns of an append pattern.
- The following has been added to the set of procedures that a pmatcher can use: boolean?, char?, list?, number?, string?, and vector?.
- A definition for pmatch-unary-or-binary-fn is supplied in the examples. (It was missing.)

2003-10-09

Project 1 is available.

2003-09-30

Andrea's office hour that is normally scheduled for Thursdays will be held Wednesday this week, from 12:30 to 13:30.
The regular schedule for the Mike's Wednesday office hour has been pushed back an hour; it is now from 13:00 to 14:00.

2003-09-27

Discussion of one of the examples has been appended to Homework 1.
More TA office hours have been scheduled: Wednesday from 12:00-13:00 and Thursdays from 11:00-12:00.

2003-09-24

Obtain or renew your SEASnet account right away, as there are occasionally delays before your account is activated.