From: jg.ruby@...
Date: 2007-04-13T11:55:13+09:00
Subject: Re: using self.attribute for writing vs reading - confusion

On Apr 12, 10:28 pm, Aryk Grosz <tennisbum2...@hotmail.com> wrote:
> Lets take this simple example
>
> class NewBook
>
>    attr_accessor :books
>
>    def initialize
>       @books = []
>    end
>
>    def some_method
>       books[0] #(  the reader for books works fine and will recall the
> class value @books, however)
>
>       books = [4,5,6,7] # ( books will not actually get assigned here
> unless I do self.books = [4,5,6,7] )
>    end
>
> end
>
> Why do you have to use self.books= on writer methods, but you can simply
> put books on reader method.
>
> Very confused. Any help would be great.
>
> --
> Posted viahttp://www.ruby-forum.com/.

In the case of "books = foo", ruby thinks books is a new locally
scoped variable.  It's a ruby language "gotcha".  To inform ruby that
you want to call the "book=" method on your object, you have to
explicitly mention the reciever: "self.book = foo"

OR, as long as you are in an instance method of that class, you can
just access the instance variable directly: "@book = foo"