Directly accessing an instance variable vs. Using an accessor method

Question

Can anyone explain the difference between accessing an instance attribute via self.attribute and by @attribute?

Answer 1

self.attribute calls the method attribute.
self.attribute = value calls the method attribute= with the argument value.
@attribute and @attribute = value get/set the value of the instance variable @attribute.

So basically they're two entirely different things.

However if you call attr_accessor :attribute it defines the method attribute to return @attribute and the method attribute=(value) to set @attribute = value. So in that case, there is no difference.

Answer 2

"Accessing instance variable directly is about two times faster than accessing them with accessor methods"

Check out the: http://greyblake.com/blog/2012/09/02/ruby-perfomance-tricks/