CSC148H  Summer 1996

Comments from the markers of Assignment 4.

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General Comments
================

The average of the day class is 64. About 1/4 of the programs are
broken. About 5 of those that work correctly use the real O.O. 
approach.

Students worked hard on this assignment. Even the program is not
working, the report still contains the design and some testing
strategies. As expected, a few people report fake testing results.
Anyway, one wouldn't get a very low mark if his/her report is okay.


Program
=======

Definition of data structures
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* Many put more than required in the export statements. For instance,
  the array of child pointers is exported.

* Some put the linked-list stuffs in the tree module. They should
  be in a separate class/module. A few even put the declaration of
  the data record in the tree module!

* Some still don't distinguish classes and types. As a result, they
  put redundant type declarations into classes.

* Have too many global variables in classes/modules for communicating
  between procedures. Should use parameter passing.


Implementation of operations
---------------------------
* I am happy to see that many can use recursion properly.

* Use of magic constants (e.g. 65 which is ord("A")).

* Lack of code sharing. For example, some don't realize that
  PRINTRANGE and PRINTPOSTAL can share the same searching routine.

* Some PRINTRANGE implementations can only handle the first 3
  characters of a postal code.


Use of inheritance
------------------
* Two ways are used to deal with the circular dependency. One is
  to split a class definition into interface and implementation.
  The other way is to define two subclasses only: INTERNAL and
  LEAF. LEAF doesn't need to import INTERNAL. Both ways are good.

* Many don't use inheritance to reuse codes. Instead, they defer
  some procedures like the initialization of the child pointers
  that can be shared by all subclasses and write two very similar
  procedure in two different subclasses.



Report
======

General Organization
--------------------
* It is nice to have a picture showing the class hierarchy and the
  import/export relationship. However, this picture is missing in
  quite a lot of reports. For those who have it, some do not explain
  the edges.

* Don't just say what the classes are. Need to explain what are
  inherited and/or overridden and why.


Tree Structure
--------------
This part is not a problem in general. However, some repeat the things
in "General Organization" here.


List Structure
--------------
* How linked lists are implemented in your program? Pointer or array implementations?

* A few confuse linked lists with leaf nodes. They write down how leaf nodes are
  handled.


Testing
-------
  Still the weakest part of the report. 

* A single data point for each operation is definitely not enough. Do at least 3.

* Many did not test the two boundary cases of PRINTPOSTAL and PRINTRANGE: 
  non-existing postal codes and empty print ranges.

* Try different prefix lengths for PRINTRANGE.

* Many testing results are still not self-explanatory. Please label your results.
  Also, it is good to use colors to highlight key things in the listings.


Overall
-------
* Many have a better idea of how to divide things into sections in this assignment.
  But some still insist on writing a 30-line paragraph containing 5 concepts. A
  few even have no headings!

* Obviously, most students have to improve their writing. It seems that
  spell checkers were used commonly. But, many need a grammar checker.
  Also, their writing styles are not technical. For example, many use
  "I" and "my" instead of "we" and "our". Also, they don't like using
  tables and bullets.