From: Chris Bailey <christopher.sean.bailey@...>
Date: 2008-08-29T05:59:41+09:00
Subject: Re: Use a string as a method call

 Thank you everyone for the quick and helpful replies! I toyed around 
with all of the suggestions and decided the following would be the best 
choice in my application.

def parse
  input = gets.downcase.chomp
  if $cmd_list.key?(input)
    send $cmd_list[input]
  else
    puts "#{input} is not a valid command."
  end
end

I have however ran into another problem and my limited knowledge of send 
(I hadn't heard of it until I read these replies) makes it difficult for 
me to debug. Some of my methods that worked perfectly before accessing 
them using send are no longer working properly. Consider the following.

cmd_list = {
            'north'   =>    'do_north'
            'south'   =>    'do_south'
            'n'       =>    'do_north'
            's'       =>    'do_south'
            'look'    =>    'do_look'
           }

def cmd_north
  $PLROBJ.xcoord -=
  showMap()
end

def cmd_south
  $PLROBJ.xcoord +=
  showMap()
end

def cmd_look
  showMap
end

If the user input is "look", the showMap method is called properly, and 
everything works as intended. However if north,south,n or s is typed 
into the system it fails to update the $PLROBJ variable but executes 
showMap() as usual and then crashes with the following error.

./commands.rb:16:in `-': nil can't be coerced into Fixnum (TypeError)
  from ./commands.rb:16:in `cmd_north'
  from bsud.rb:33:in `send'
  from bsud.rb:33:in `parse'
  from bsud.rb:58:in `main'
  from bsud.rb:63


$PLROBJ.xcoord and ycoord are initiated with a value of 5 and as far as 
I know there is nothing that would ever make them 'nil'. I have no idea 
what this problem is =(


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