Help in understanding encrypting the password

I am currently on page 183 on the pdf version and I am a little confused about this method. Looks like this is an instance method and not a class method, but why is the salt and encrypted_password need the self keyword in front of it. Would really appreciate it if someone could give me an idea what’s actually happening.

def encrypt_password
  return if password.blank?
  if new_record?
    self.salt = Digest::SHA1.hexdigest("--#{Time.now}--#{email}--" )
  end
  self.encrypted_password = User.encrypt(password, salt)
end

Dhana,

The encrypt_password method is indeed an instance method. In Ruby, the keyword self refers to the current object. This is similar to calling $this->salt = ... in PHP. Much of the time in Ruby, we don’t need to prefix the method with self. because self is implied. In this very method we refer to the email method without using the self. prefix, and Ruby implicitly knows to check instance methods for the value of email.

The difference is that in the case of self.salt = ... and self.encrypted_password = ..., we’re assigning a variable. In this case Ruby doesn’t know if we want to set the local variable salt or the salt method on the current User object. The only way to let Ruby know that we want to assign the User’s salt method is to explicitly use self.salt = ... to do so.

The self keyword is used in the context of both classes and objects because classes are in fact objects themselves in Ruby.

Here is an article that explains self a little better:
http://rubylearning.com/satishtalim/ruby_self.html

Hope this helps!
Derek