From: Lyle Johnson <lyle@...>
Date: 2002-04-20T07:30:07+09:00
Subject: Re: String to method name

> Thanks a lot... it does help, a little.  The problem is, I am trying to
> feed this stuff into (at the moment) a global variable in a block, like
> this:
>
> FILE.each_line do |line|
>   (badGuyType,badGuyShow,badGuy) =
line.scan(/^(\S+)\s(\S+)\s(.*)$/).flatten
>   $senslessNames[badGuyType] = {badGuyShow => badGuy}
> end
>
> where the file looks like lines of this:
>
> mutantMonkey powerPuffGirls Mojo Jojo
> mutantMonkey planetOfTheApes Ape Number 3
> evilCat powerPuffGirls kitty
> evilCat planetOfTheApes Ninja Kat 5000
>

Try this block instead:

    # Be sure to initialize it to an empty hash
    $senslessNames = {}

    # Read file and store inputs
    FILE.each_line do |line|
      badGuyType, badGuyShow, badGuy =
line.scan(/^(\S+)\s(\S+)\s(.*)$/).flatten
      if $senslessNames.has_key? badGuyType
        $senslessNames[badGuyType][badGuyShow] = badGuy
      else
        $senslessNames[badGuyType] = { badGuyShow => badGuy }
      end
    end

The problem with your original version is that for a given "badGuyType" key,
you're always overwriting the previously created hash for that key. The
line:

    $senslessNames[badGuyType] = { badGuyShow => badGuy }

creates a new Hash object (the RHS of this assignment) with only one
key-value pair and stores that at the specified location in the
$senslessNames hash. My modified version (above) checks to see if the bad
guy type we just read is already present as a key in the $senslessNames
hash. If it is, we just add a new key-value pair to the already-existing
hash at that location. If it isn't, we know it's safe to create a new hash
as before.

Now might be an excellent time for you to check out the chapter in
"Programming Ruby" about different container types, including the Hash:

    http://www.rubycentral.com/book/tut_containers.html

Hope this helps,

Lyle