ActiveRecord: why does '' and 'name' both work?

I'm trying to figure out why both '' and 'name' work in a
model class. For example:

class Category < ActiveRecord::Base
  before_save :set_permalink
  def set_permalink
    # both work
    self.permalink = name
    self.permalink =
    # doesn't work
    permalink = name
    @permalink = name
    @permalink = @name
    self.permalink = @name

I thought that attributes in a class were set via instance methods,
but 'self.permalink = @name' doesn't work, but 'name' (which looks
like a local variable to me) works fine. And self.permalink works, but
@permalink doesn't.

I'm still new to Ruby and classes so it's probably something simple I
don't understand, so any help would be appreciated.

Basically name and are interpreted by ruby as methods…

because your model when mapped to its corresponding table has a column called ‘name’, rails creates the relevant method

Therefore your reference to name and are calling the same method… as name (without the self.) is scoped to the instance method (as its inside an instance method itself), and self evaluates to the instance, therefore it calls the instance method ‘name’…

both work

self.permalink = name <-- calls method name, and its value is passed to the method ‘permalink’ (again, not an variable really)

self.permalink = <-- calls same method… as self. evaluates to the instance

doesn’t work

permalink = name <-- ruby is probably getting confused here… which is probably why its not working…

@permalink = name <-- again this is probably being set … but it wont update your model as it is saved… because @permalink is a var self.permalink is the method you need to call to update your model…

@permalink = @name <— again they are not instance vars. … so @permalink => nil but you wont see it in your db…

self.permalink = @name <-- @name doesnt exist … so will be nil…

I hope that makes sense… sunday afternoon in the office has left my brain a bit fried… (mainly because im writing actionscript…)

Good luck!