600.321/421, Object Oriented Systems
Smalltalk Assignment 2: Mind-Boggling
Due: Thursday Oct 8th, by midnight

Your assignment is to code a version of the game "Boggle".
Here is how Boggle is played, in case you haven't ever experienced the Joy of Boggle.

• The game is played with a 4x4 grid of dice which have letters on them. To start, the dice are shaken and you get a random letter in each slot, looking something like

  a	e	f	n
  w	r	p	o
  i	y	m	s
  v	e	x	k

• Players then make a list of words of three or more letters as fast as they can that can be found contiguously in the cubes. For instance, "warps", "ware" and "are" are legitmate words in the above: diagonal moves are possible, and it it is even possible to backtrack to give "ere". "fee" is not a word in the above, a move must go somewhere. Neither is "pow" -- there is no wraparound or hopping-over. Words can be any lowercase word in a dictionary, but must be three or more letters.
• After 3 minutes have passed, time is up. The player with the most unique words wins.

• For now the fancy user interface is going to be the workspace. Here is how the user will play the game.

  X := Boggle start "execute this with print it menu option"

  This will start the game and print out the 4x4 grid of letters in the workspace. The (global variable) X is a Boggle object: start is an object creation protocol.
  Note that the printOn: method for Boggle objects is thus going to have to print the grid.
  Then for each guess, the user will "do it" to a statement of the form

  X wordGuess: 'ware'

  which will add 'ware' to the list of guessed words.
  When the timer expires, the message 'GAME OVER; you had 12 correct guesses' will automatically appear in the transcript (assuming 12 correct guesses were made; incorrect guesses are ignored).
• That's IT. A user should be required to do nothing other than filing in your code and the exact above actions to play a game.
• To be nice to the graders, please allow

  X correctGuesses

  after the game is over to return the number of correct guesses. In the middle of a game this method can return anything you want. Also, to be doubly nice, please add a method Boggle startWithGrid: 'aefnwrpoiymsvexk' to start the game, but with the grid letters as above instead of a random grid. (10-2 clarification: this method is a variation on start -- it does the same thing but starts with a fixed grid. You could make your start method generate a randon string and call startWithGrid:).
• You can assume all letters are lower case.
• For your word list, use the dictionary here. This dictionary is not the most complete, it does not include plurals or prefix/suffix variations. Words are separated by cr's, and it does not include words of length less than 3.
• In order for us to easily test your code, please assume the dictionary file name is in the global variable DictFileName. This variable will probably contain just 'dict', but you can make it a full path such as 'b:\oos\assignment2\dict' if you desire.

• aStream nextPut: Character cr.

  will be helpful for printing the Boggle grid: this will put a newline on aStream.
• The following chunk of code is all you need to know about running a timer process in Smalltalk:

  [ (Delay forSeconds: 10) wait.
     Transcript show: 'beep!'; cr ] fork.
     Transcript show: 'notice how things right after the fork immediately run.';cr
         

  Paste and execute this code to see what it does. Instead of beeping, you should send a message which ends the game and returns the number of correct guesses.
• Remember that the class method named initialize is executed when that class is filed in. You can do any initialization you want to do there.

•        dictFileName := 'dict' asFilename.
         dictStream := dictFileName readStream.
         

  opens the filename "dict" as a stream for reading (of class ReadStream). Note, for this code to work, the filename must be in the same directory/folder as where visualworks was launched from.

  dictStream upTo: (Character cr)

  then returns a string of all the characters up to the next cr on the stream, and

  dictStream next

  advances the stream one character.
• The code 97 asCharacter returns the character $a. The code 97.0 asInteger returns 97.

Design and Coding Style

An initial grid of random characters must be generated. A list of word guesses must be maintained during the game play, and both checked against the 4x4 grid to make sure the word occurs, and checked against a dictionary, at the end of the game. Checking a word against the grid will require finding all possible starting points for the word and traversing from there in all possible next directions to see if there is any direction to proceed for match. . . .

At this point in your Smalltalk coding career, it is good to go overboard with keeping to the spirit of the high-level description -- make method names as evocative as possible, and make a class for every different possible object-concept.

Please use hashing to implement a fast word dictionary lookup (big hint: Smalltalk Sets use hashing for lookup...).

See the coding style suggestions in lecture. You will be expected to follow those points.

Submission Instructions

For your code, use the file out as.. menu option on the class category list to file out your class category as Assignment2.st, and then submit this file from hops via the precise (no exceptions in names, please) hops command

~scott/bin/submit Assignment2 Assignment2.st

You will need to ftp your files to hops first if you are working on some other machine.

Don't submit a .im file, they are too big! Use the file in/out tool instead.

You can check what files you submitted via

~scott/bin/query