From: poopdeville@...
Date: 2006-10-11T05:00:23+09:00
Subject: Re: Using configuration files (replacing shellscripts)

Jim Crossley wrote:
> Hi...
>
> Karl Voit <devnull@Karl-Voit.at> writes:
>
> > I want to use configuration files in order to save values,
> > directories, and files. I did some googeling to find out that the
> > ruby community often suggests ruby-files (hashes) to save
> > configurations. These rb-files are read in by interpreting. (btw,
> > anyone suggests a cool part of code for this with errorhandling and
> > so on?)
>
> If I understand what you're asking for, you may want to have a look at
> YAML.  Your config file can look like this:
>
> ####
> adapter:   mysql
> database:  demodb
> username:  karl
> password:  pa$$w0rd
> socket:    /var/lib/mysql/mysql.sock
> ####
>
> Turning that file into a ruby hash is a one-liner...
>
>   require 'yaml'
>   dbconfig = YAML::load(IO.read('config.yml'))
>   assert_equal('karl', dbconfig[:username])
>
> Jim

I wrote something a bit more general.  It assumes that the yaml file
serializes a Ruby hash.  You'd probably want this to be a singleton
class, but my uses don't require that.  Perhaps the OP would find it
useful:

class Parameters

  require 'yaml'
  def initialize(config_file)
    @config = YAML.load(File.open(config_file))

    # This creates a global variable for each entry in the yaml
configuration file.
    # I recommend that this interface be deprecated in favor of using
accessor syntax.
    # E.g. creating a Parameters object config = Parameters.new and
calling accessors
    # on config.

    @config.keys.each do |parameter|
      eval('$' + "#{parameter} = @config[parameter]")
    end

    # This creates an accessor for each of the configuration entries in
the yaml
    # configuration file.

    @config.keys.each do |parameter|
      eval("@#{parameter} = @config[parameter]")
      self.class.class_eval {attr_reader parameter}
    end
  end
end