Programming Assignment #1

Discuss at PA1 Collaboration Space. Due in class on July 24.

The user needs to create a spreadsheet that can compute the sum of a row or column, the average of a row or column, and, as a special case, the sum or average of two or more specific cells of a spreadsheet. Cells are specified by strings of the form "A1" -- a letter and a digit. There will be no more than 26 columns (A-Z) and 9 rows (1-9). You may assume that all cell specifications will be correct. The user would like to use these spreadsheets with Workspace code that looks like this:

| ss1 |
ss1 := Spreadsheet new.
ss1 cell: 'A1' put: 15.     "Puts 15 into cell A1"
ss1 cell: 'A2' put: 30.
ss1 cell: 'A3' put: 75.2.
Transcript cr; show: (ss1 sum: 'A') printstring.  "Prints the sum (120.2) to the Transcript"
Transcript cr; show: (ss1 cell: 'A1') printstring. "Prints 15 to the Transcript"


ss1 cells: #(24 76.4 19 37 89) putIn: 'B'.  "Fill five cells B1..B5 of the spreadsheets with these values"
Transcript cr; show: (ss1 average: 'B') printstring. "Prints the average (49.08) to the Transcript"


"Create a cell that sums the values of two Spreadsheets"
ss1 cell: 'C1' sum: 'A'.
Transcript cr; show: (ss1 cell: 'C1') printstring. "Prints the sum 120.2 to the Transcript"
ss1 cell: 'A4' put: 89.9.  "Add a fourth cell to ss1 column A."
Transcript cr; show: (ss1 cell: 'C1') value printstring. "Prints the updated value 210.1"

In summary, methods that spreadsheets should understand include:

• cell:put: takes a cell reference and stores a value there.
• cells:putIn: takes a literal array (p. 19 Hopkins & Horan) and stores it in consecutive cells of the given row or column (starting from the first, over-writing anything there.)
• cell:sum: and cell:average: (the latter is not shown here) tells a specific cell to compute the sum or average of a row or column reference (e.g., 'A' or '1').
• cell: takes a cell reference and returns the value there.
• sum: takes a row or column reference (e.g., 'A' or '1') and returns the sum of that row or column
• average: takes a row or column reference and returns the average of that row or column

  Special notes to consider:

  • References to cells that have not been filled should return 0.
  • Hint: A good OOA should consider use of generalized formulas instead of special symbols #sum and #average. (And these would be good topics to address in the Reuse section of your report!)
  • Strong Hint: You will lose points if you have only a single class in your system.

  HIC for Spreadsheets

  The user is pretty comfortable entering Smalltalk code, so it's okay to always use cell:put: and cells: messages for entering values into cells. However, the user does want to see:

  • The cells and values in a given spreadsheet, in order.
  • How the value is determined if the cell is a Sum or Average cell.

  This can be done fancy (e.g., with scrolling lists) or simply (e.g., a big display box with formatted text in it.) For the above, a window that contained the following would do:

  
  A1: 15 - B1: 24 - C1: 210.1 (sum 'A')
  A2: 30 - B2: 76.4 - C2: 0
  A3: 75.2 - B3: 19 - C3: 0
  A4: 89.9 - B4: 37 - C4: 0
  A5: 0 - B5: 89 - C5: 0
  

  Notes:

  • If there's nothing in columns D through Z, don't show me anything in D through Z.
  • If no column has anything after cell 7, don't show me cell rows 8 and 9.
  • If you can line things up nicely so that the TA can figure out what you're doing quickly, why, he might appreciate that!

  HINTS AND SUGGESTIONS

  • You will need the Coad and Nicola User Interface Package to complete the user interface.
  • You may find that the STABLE cases on spreadsheets to be useful. Very useful. They implement one-dimensional spreadsheet rows. Your spreadsheets happen to be two-dimensional. It would be wonderful if the previous students built their spreadsheets so that the rows could be reused in a 2-D spreadsheet.
  • To parse strings, you can chop them up with at:, e.g., 'a1' at 1 returns the character $a. See Chapter 15 of Hopkins and Horan.
  • You might want consider storing spreadsheet columns (or rows) in dictionaries indexed by the row or column reference. See p. 139 of Hopkins and Horan for more on dictionaries.
  • Grading will be based on "grading" page.
  • Please follow "DesignDocs" standards.
  • Discuss at PA1 Collaboration Space.
  • Due on July 24 in class. Please mail your code to cs2390@prism.gatech.edu with a turn-in code of pa1, i.e., your subject line should look like: "TI,pa1,123456789" Please bring your written documentation to class on July 24.

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