From: Wilson Bilkovich <wilsonb@...>
Date: 2005-12-31T07:34:40+09:00
Subject: Re: Another Newb asks questions.

On 12/30/05, Joseph Divelbiss <joseph@joseph.net> wrote:
> Ok, recently started "trying" to learn this wonderful language, but am
> experiencing major problems with a section of code that I think "should"
> work.. and my brain is so convinced that I did it correctly that I can't
> see some obvious error.  Ive isolated the problem to this single section
> of code.. what do you all think?
>
>
> #This section reads data files and saves odd lines as the key, even
> lines as the value for a hash.
>
> if Dir["/Program Files/.../data/"].last != nil
>         script_data_dir = "/Program Files/.../data/"
> end
> build_hash = Proc.new do |type|
>                 hash.new = type_hash
>                 file.open("#{script_data_dir}type.dat", "r") { |file|
>                         data = file.readlines
>                         data.delete_if { |line| line.chomp.empty? }
>                                 until data.empty?
>                                 $type_hash[data.shift.chomp] = data.shift.chomp
>                                 end
>                 }
> end
> build_hash.call(test)
> end
>

This solution uses the 'enumerator' module, included in the standard library.

require 'enumerator'
Dir.chdir(script_data_dir)
type_hash = Hash.new
File.open('type.dat','r') do |file|
  file.each_slice(2) do |odd, even|
    type_hash[odd.chomp] = even.chomp
  end
end

each_slice(2) is taking each pair of lines in the file, and passing
them to the block.  So, [line1, line2], then [line3, line4], etc, etc.
You should probably also have a check in there to make sure the file
has an even number of lines.

You can also use File.exists?() to check for the presence of a directory.
abort "Oh no!" unless File.exists?("C:/Program Files/something/data_dir")