From: lists <lists@...>
Date: 2009-03-19T10:11:19+09:00
Subject: Re: Is this how you start a hash?


On Mar 18, 2009, at 7:50 PM, Power One wrote:

> I'm looking at the code below but still not clear about how this hash
> forms!  The author of a ruby book I read claimed that the code forms
> hash.  Is it?
>
> #not complete code, if you try to use it, it won't work!
>
> require 'yaml'
> require 'wordplay'
>
> class Bot
> attr_reader :name
>
> def initialize(options)
> @name = options[:name] || "Unnamed Bot"
> begin
>  @data = YAML.load(File.read(options[:data_file]))
> rescue
>  raise "Can't load bot data"
> end
> end
> end
>
> So, when you created hash, don't you have to initialize it with an  
> empty
> hash?  For example:  @name = {}?
>
> Also when I try to use a snippet in irb:
> @name = options[:name] || "Unnamed Bot"
> NameError: undefined local variable or method `options' for  
> main:Object
>  from (irb):1
>  from :0
>
> options is also in File.read(), it's acting like adding more element  
> to
> a hash.  Am I right?  Though irb tells a different story as if it's  
> not
> how you starting a hash.
>
> I'm confused!
> -- 
> Posted via http://www.ruby-forum.com/.
>
>

Yes, you'd normally create a new has with either Hash.new or hash =  
{}.  The method above is expecting that an already populated Hash be  
passed as its argument (internally referred to as the options  
variable).  So here's how you'd use the Bot class:

Bot.new(:name => 'My Bot', :data_file => '/tmp/file.yml')

Maybe this helps you see the Hash more clearly:

Bot.new({:name => 'My Bot', :data_file => '/tmp/file.yml'})

or even:

my_options = {:name => 'My Bot', :data_file => '/tmp/file.yml'}
Bot.new(my_options)

Hope this helps.