From: HiddenBek <scott.wadden@...>
Date: 2007-12-01T00:15:02+09:00
Subject: Re: problem with 'self'. behaves different on setting and gettin

Here's a small example to illustrate Jari's point:

class User
  attr_accessor :x

  def foo
    self.x = 1
    puts x      # => 1
    x = 2
    puts x      # => 2
    puts self.x # => 1
  end
end

User.new.foo

Any assignment without an explicit receiver will set a local
variable.  You also need to use self if the method you're calling is
shadowed by a local variable with the same name, as in my example
above.  Finally, you must use self if the method you're calling is a
reserved word, such as self.class.

Page 86 of the Pickaxe book (Programming Ruby) talks about this.

On Nov 30, 10:33 am, Jari Williamsson
<jari.williams...@mailbox.swipnet.se> wrote:
> Michal Gabrukiewicz wrote:
> > so my 1st question is: why doesnt the 'set_foo' method calls the 'x'
> > method if i remove the self?
>
> Because it now thinks that x is a local variable. This is one of the
> basics of Ruby.
>
> If you use NetBeans, the editor will alert you about these kind of
> things in the colored syntax.
>
> > THE INTERESTING THING: 'get_foo' works with 'x' and 'self.x'
>
> Yes, but with different result behind the scenes. 'x' is the same as
> 'x()', while 'self.x' is the same a '@x'
>
> > and the 2nd question: when should i use self now and when not and why is
> > there this strange behavoir?
>
> You should use self when a left-side argument can be interpreted as a
> local variable.
>
> Best regards,
>
> Jari Williamsson