Programming assignment 1

Discuss at http://guzdial.cc.gatech.edu:8080/cs2390.22

Problem Statement

The user needs to create 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 (e.g., no one references a cell that hasn't been created yet, all column references are uppercase letters, etc.) 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 solve: 'SUM(A1:A3)') 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 solve: 'A1+B1') printstring. "Prints 39 to the Transcript"
Transcript cr; show: (ss1 solve: 'AVERAGE(B1:B5)') printstring. "Prints the average (49.08) to the Transcript"


"Create a cell that sums the values of two Spreadsheets"
ss1 cell: 'C1' solve: 'SUM(A1:A3)'.
Transcript cr; show: (ss1 cell: 'C1') printstring. "Prints the sum 120.2 to the Transcript"


ss1 open.  "Opens up the HIC View on the Spreadsheet -- ADDED 2/9"

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 and stores it in consecutive cells of the given row or column (starting from the first, over-writing anything there.)
• solve: takes a formula as input and returns the result. Formulas are either simple equations with only two entries (CELL+CELL, CELL-CELL, CELL*CELL, CELL/CELL) or are one of two functions, AVERAGE or SUM, applied to a range of cells in the same column (A1:A5).
• cell:solve: tells a specific cell to compute its value from the given formula.
• cell: takes a cell reference and returns the value there.

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, not just the limited forms used here. (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 formula.

This is what the user should see after the ss1 open above. I don't recommend using Squeak-UI.st for this -- use a StringHolder as discussed in the CS2390 CoWeb. Do this in a really simple way, e.g.:

A1: 15 - B1: 24 - C1: 120.2 (SUM(A1:A3))
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

• This is a variant of the Simple Spreadsheet at http://guzdial.cc.gatech.edu:8080/cs2390.42
• You may find that the STABLE cases on spreadsheets to be 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.
• You might want consider storing spreadsheet columns (or rows) in dictionaries indexed by the row or column reference.
• Grading will be based on Grading Policy page.
• Please follow Design Documentation standards.
• Discuss at PA1 Collaboration Space.
• Due on Feb. 12 in class. Submit your code via the turnIn system. Please bring your written documentation to class on Feb. 12.