Session 23

More Experience with Lists

CS 1510
Introduction to Computing

Code Review of Homework 9

Homework 9 was shorter than its predecessor, but created offered some interesting challenges. How can we print out the number of matches before printing the lines that match? How do we do the match? How do we organize the code?

A great way to improve as a programmer is to study code. There are many variations:

• We can learn from someone else's implementation of the same program we have written. First, we see things to emulate. Second, we see things not to do -- and come to appreciate why advice we don't follow is good advice.


• We can also learn from other people reading our code. Different eyes see new wrinkles, as well as the good things we do.

Let's review a program. With the program you are given, do the following:

• Read the code individually.
  • Note at least two things we like about the program.
  • Note at least two things the programmer could do to improve the program.
  • Note anything we don't understand in the program.


• Organize into groups of three.
  • Discuss the things you all like about the program and the things you think the programmer could do to improve the program.
  • Answer your colleagues questions about the program if you understand something they don't.


• Note at least one thing that you learned from this program, or one thing that this program reinforced for you.

... do a group review. What do you like? Ways to improve the code? Questions about the code? Comments?

• one pass better than two...
• line wrap, Python structure, and reading code
• use of tuple in lieu of a list
• defs at the top, with main program clearly marked
• variable names... i

... advice on work habits. Starting late. Asking questions. Doc, it hurts when I go like this.... Sometimes, the best advice really is, So don't go like that. Even if it leaves me open to this:

How can I help you not hit yourself on the head?

Using Lists to Improve Our Code

... my solution didn't use lists. Instead, it built a string to print.

... some weaknesses. How I prepare lines and strings for matching. Embedding formatting into the processing code. search() function having to open and close the file.

Each function should do one thing.

... advantages of print_result() function. Frees search() of those details. A single place for this conceptual action. Easier to change or replace the output behavior.

... one more step issue? Create a function called search_by_filename() to handle input file open and close. What are the advantages of this step?

Look at structure of the program:

                                main
                                 |
               --------------------------------------
              |                  |                   |
          get_files      search_by_filename    print_result
                                 |
                                 |
                               search
                                 |
                                 |
                            multi_find

... decompose the problem into conceptual pieces. Write a function for each piece.

Other Assignments

Any questions about Homework 10? Please take baby steps! Some of these may take a while to run... How might you make your code faster?

Return Homework 8. We looked at my solution last week. Here is the Python file, if you'd like to study more. It is never too late to ask questions, if you have them.

Image Credits

The image of the man hitting himself on the head is available for purchase through Vecto.rs.

The cartoon of the two convicts comes from The New Yorker and is available for purchase through the Conde Nast store. (The New Yorker has published many great one-panel cartoons over the years.)

(return to code review)

Wrap Up

• Code -- today's code file


• Reading -- Read Section 7.7, pages 321-324, and Section 7.9, pages 327-337. We are skipping Sections 7.8, 7.10, and 7.11.


• Homework -- Homework 10 is available and due Friday.


• Exam -- Exam 2 is one week from Thursday, November 20.