Can anyone explain the difference between accessing an instance attribute via self.attribute and by @attribute?
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2 Answers
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.
2 Comments
Phrogz
Note that it is generally recommended to use
self. (unless you're writing the getter/setter method) even if you currently have attr_accessor. This protects you from additional refactor work and bugs if you later change the accessor method(s) to do more than just get/set the instance variable. (Or if someone else patches or subclasses your work.)
Jason Noble
One of the bugs Phrogz is talking about is if you simply call attribute = _____ instead of self.attribute = ______ you are setting a local variable instead of the instance variable.
"Accessing instance variable directly is about two times faster than accessing them with accessor methods"
Check out the: https://www.greyblake.com/blog/2012-09-01-ruby-perfomance-tricks/
1 Comment
nbkhope
The link is broken. This one works: greyblake.com/blog/2012-09-01-ruby-perfomance-tricks