May 2001 Programmer's Challenge

Basic Klondike

Mail solutions to: progchallenge@mactech.com
Due Date: 11:59pm ET, Tuesday, 1 May 2001

I'll admit it. I got into programming in an unusual way. Predating the web by a few (!) years, I didn't start with HTML or Perl. Nor, unlike some of my colleagues, did I start with a PC with toggle switches where the keyboard input should have been and with LED output instead of a video port. No, I actually started by reverse engineering machine code programs, and then discovering assembly language, and only later high level languages like FORTRAN and COBOL.

But somehow, through all that, I missed BASIC as a language, only discovering it much later, and never developing much of an attraction for it. But BASIC hasn't gone away, it is still alive and kicking as a modern object-oriented development environment. This month we're going to have some fun with BASIC, courtesy of the folks at REAL Software.

We've been using CodeWarrior for the Challenge for some time now, starting with C, expanding to C++, and allowing Pascal even though Metrowerks (or should I say Motorola) has deprecated that language. We've accepted Java solutions, although with some restrictions. But we've never even considered BASIC — after all, BASIC is a beginner's language, not used by serious programmers, right? Well, maybe not.

It turns out that there are real applications being written in BASIC. I discovered one, MacDynDNS, when I was forced to change DSL providers to one that didn't grant static IP addresses. So, when I was contacted by the folks at REAL Software about holding a REALbasic Challenge, I decided to experiment with their environment.

We're not in the business of endorsing products, but a little experimentation demonstrates that REALbasic is pretty cool. It converts BASIC into a fully object oriented language, and the environment does a surprising amount of the work required to create an application for you. They provide a nice tutorial that helps you quickly start using the environment. And they offer a free 30-day demo (see http://www.realbasic.com/), which we're going to take advantage of with this month's Challenge.

The prototype for the code you should write is …, well, there isn't one. Your task is to build a REALbasic application that lets me play the card game Klondike. Klondike is a solitaire card game, the object of which is to build up all 52 cards onto four foundation piles in ascending order, by suit, from the Ace to the King. As a reference implementation for what constitutes legal play, I'm using the shareware game by Mike Casteel available at www.casteel.org. The requirements? You need to display a graphical representation of the game — the cards in the tableau, the four foundation piles, the deck, and the top three cards revealed from the deck. You need to support playing cards and stacks of cards by dragging them from one pile to another. You should highlight the destination when a card is dragged to a position where it can legally be played and, of course, allow only legal moves to be made. You need to provide multiple levels of Undo and Redo. You should provide menu items to start a new game, to replay the previous game, to save the game state, and to resume playing a previously saved game. Your application should be user friendly, warning the user, for example, when s/he is about to quit an unfinished game. You should provide preference controls that allow me to turn over one card at a time instead of the usual three and control whether scoring is displayed.