Difference instance variable @ or self.

I’m pretty new to Ruby myself, I’ve kinda learned as required so I’m patchy.

From what I’ve seen however, I think ‘self’ is relative to the current scope, i.e instance or class. Where as @ is always in instance scope.

Ian.

self is the object itself.

self.name is saying that there’s a public method on self to be called (attr_reader :name)

@name says ‘get the instance variable @name for this class instance’

Use ‘self’ pretty much the same way you’d use ‘this’ in Java or C++, though not in the cases that you can use @ (passing yourself to another method is the most used example).

Jason

Hi --

First: I'm new to Ruby

Simple model:

class Product < ActiveRecord::Base

  def save
    STDERR << "save: " << @name << "\n"
    STDERR << "save: " << self.name << "\n"
  end
end

I thought that both lines should give the same result...

I'm pretty new to Ruby myself, I've kinda learned as required so I'm
patchy.

From what I've seen however, I think 'self' is relative to the current
scope, i.e instance or class. Where as @ is always in instance scope.

self is the "default object". There's always one and only one self at
any point in a Ruby program.

Since classes are objects, self can be a class:

   class SelfTest
     p self
   end # => output: SelfTest

Instance variables are a way for individual objects (including Class
objects) to store information and maintain state. Every object has
its own instance variables.

There's a tight connection between instance variables and self:
whenever you see @var, @name, etc., you're seeing an instance variable
that belongs to self.

self is the object itself.

self.name is saying that there's a public method on self to be called
(attr_reader :name)

All it really says is that you're sending the message 'name' to the
object self. Usually you do that in cases where there's a
corresponding method -- but not always.

attr_reader isn't connected to this; there are many methods you can
call on objects that aren't created with attr-reader.

@name says 'get the instance variable @name for this class instance'

More precisely: @name is the instance variable @name belonging to
self (whatever self is at that given moment in runtime).

David