From: Stefano Crocco <stefano.crocco@...>
Date: 2007-05-29T20:44:07+09:00
Subject: Re: operator =>

Alle marted� 29 maggio 2007, Gian Holland ha scritto:
> Hi I have a beginner question
>
> What does the => operator do?
>
> here is the example code from the book
>
> class Product < ActiveRecord::Base
>   has_many :orders, :through *=>* :line_items
>   #...

=> is not an operator, its simply the syntax used to create hashes:

h = {:a => 1, :b=>2}

creates an hash with keys :a and :b, corresponding to values 1 and 2 
respectively. When you need to pass an hash as the last argument of a method, 
ruby allows you to omit the braces, so your call to has many means:

has_many( :orders, {:through => :line_items} )

In other words, you're passing two arguments to the method has_many: the first 
is the Symbol :orders; the second is a Hash with one key (:through) and one 
value (:line_items)

Stefano