From: Hans Fugal <fugalh@...>
Date: 2006-03-12T02:23:43+09:00
Subject: Re: attribute setters for instance variables

eliben@gmail.com wrote:
> Hello,
> 
> The Pickaxe book presents the following example:
> 
> class Incorrect
>   attr_accessor :one, :two
>   def initialize
>     one = 1
>     self.two = 2
>   end
> end
> 
> obj = Incorrect.new
> 
> p obj.one
> p obj.two
> 
> The first thing printed is 'nil' and not '1' since "one = 1" assigns to
> a local variable of method initialize instead of the instance variable.
> So far it's clear.
> Now, they propose a solution: to use self.one instead of just one.
> Won't be using @one simpler and also correct ? What am I missing ?
> 
> Thanks
> 

@one = 1 is setting the instance variable itself, and that's fine for 
accessors. If you want to do something special on =() then you will want 
to use the self.one style. e.g.

def Foo
   def one=(n)
     @one = n+42
   end
   def initialize(n)
     self.one = 0 # @one == 42
     @one = 0     # @one == 0
   end
end