unnecessary.rb

# unnecessary.rb - Josh Sandlin - 3:13PM - 1/15/2010
# An interpreter of the Unnecessary language

# raised when the source file is present
class CriticalError < Exception; end

# core of the interpreter
class Unnecessary

  attr_accessor :source_file

  def initialize( source_file )
    @source_file = source_file
  end

  def parse
    raise CriticalError, "The file exists!" unless !File.exists? @source_file
  end

  def execute
    begin
      parse
      puts "Program executed successfully!"
    rescue CriticalError => msg
      puts "CRITICAL ERROR: #{msg}"
    end
  end

end

interpreter = Unnecessary.new( ARGV.shift )
interpreter.execute