A young friend (YF) of mine was having a problem with a programming assignment from a large local university (LLU) and gave me a call the other day for some help. We spent a couple of hours together going through the piece that he was having issues with and finally got everything pretty much working. This episode though showed me that we don't necessarily teach the right things in college concerning how approach a program. I thought I'd take a few posts and show how I might tackle a problem like this. Not everyone will find this way of doing things appropriate and I wouldn't use it in certain cases, but it may help some of you in some cases.
Here's the problem as given:
Assignment Details
Homework 1 - Non-GUI Tower Defender
Players start with a fixed amount of money, in less they are a returning player. In that case, they are to start with the money they ended up with, or they can start over, if they wish.
Towers:There are to be 4 types of towers. Each has a different capability - you get to decide. Each has a different price - that you decide. A player starts the game by deciding which towers they want and where they are to be put. Given that the path for Creeps is only from left to right, towers can be above, or below, the path. The player gets to decide that, and the "x-direction" for the tower location.
Since this first assignment is not graphical - only command line - the Creep path is straight from left to right. You are to use keyboard characters as your graphics to display what is happening - tower location, and Creep location.
Creeps:Creeps may move one, or more, squares, from left to right each "turn". You get to decide how big squares are. Too big, and Creeps will easily get to the base - which is on the right side of the window. Creeps start from the left side of the display window. You are to have three (3) types of Creeps. Their behavior is up to you, but just moving faster, or slower, does not qualify as a different Creep type. Each Creep is worth a different amount of money - depending on how hard they are to kill.
Statistics: You are to track the number of Creeps killed (for each Creep type), the total number of times this player has played, the total amount of money they have spent, and the total amount of money they have earned. You may choose to have additional statistics.
There are a few things here that are worth noting. First the requirements are pretty loose. You have some options for doing things how you like (this may be good or bad depending on your temperament. Second there are a couple of things that don't make sense. We have the "x-direction" for the tower location. I'm pretty sure that what's meant is the "x-position", but if I were doing this for a grade at LLU, I'd check with the prof. I checked with YF and it sounds like since the towers don't move, the x-position is what is meant.
As a first cut, I'd spend my time working on the "logistics" of the program. What do I mean by that? Well, we'll have a main program that loops getting input from a player. We're going to have to create a player, give her some money, be able to save her totals when she quits, and on initialization, we're going to have to check if she's played before and if so if she'd like to resume or start a new game.
With that out of the way, here's what I came up with (this is in Ruby, YF for LLU had to write this in Java).
class Tower
end
class Creep
end
class Game
end
class Player
def initialize(name)
@name = name
@dollars = 100
@file_name = "#{@name}.txt"
if File.exist?(@file_name)
print "Welcome back #{@name}. Would you like to resume(r) or start a new game(n)?"
command = gets.chomp
case command
when "r"
puts "Resuming from #{@file_name}"
File.open(@file_name, "r") do |player_file|
line = player_file.gets
if line != nil
name_f, @dollars = line.split(",")
puts "Resume: #{name_f}: Dollars"
else
puts "Could not read line"
end
end
when "n"
puts "Starting new game"
end
end
end
def save
player_file = File.new(@file_name, "w+")
player_file.puts "#{@name}, #{@dollars}"
player_file.close
end
def to_s
"name: #{@name}, dollars: #{@dollars}"
end
end
if __FILE__ == $PROGRAM_NAME
print "Name: "
name = gets.chomp
player = Player.new(name)
puts "#{player}"
while true do
print "Command: "
command = gets.chomp
case command
when "q"
player.save
break
end
end
end
You can see that I put the requirements at the top so they're pretty much always available for checking (you obviously can't do this with really big requirements, but when you can, it's not a bad idea). There are place holders for the classes that I think we'll have, but those may change. The one that's filled out, the Player class, has just three methods. initialize(), sets the player up and checks if the do/don't already have a saved game, save() saves the players current data, and to_s() let's us print out their data in a readable format. As we go along, these may (really will) change and get refactored, but for now, they'll suffice. The main program asks the user for their name and creates a player. We then start the main loop that just gets a command (here only the quit command) and processes it. Quit simply saves the players data and breaks out of the loop which then exits.
This would probably take less than 1/2 an hour for someone who knows the language they're working in fairly well. What is does though is provide us with places to hang major pieces of the game going forward.
Let me know if you have questions or comments and look for the next edition where we'll add in a bit more functionality to the program.
