What is the conventional way to access instance variables within an object in Ruby?

Question

Consider the following code:

class Dog
  attr_accessor :name, :color

  def initialize(name, color)
  end
end

Within a Ruby object, is the convention to access the instance variable directly (ie @name = name) or to use the setter/getter methods (ie name = name)?

The former is more clear to me, but if you implement your own setter/getter methods (eg to increment a class variable at the same time) then you end up having to use both approaches (ie @name = name ; color = color).

What's the convention within the Ruby community? How should I write my code to make it clear to others who will read it?

Answer 1

Using name = value is an error, because that creates a local variable named name. You must use self.name = value.

As for convention, you can only get away with using @name if you can guarantee that the accessors will always be lightweight attr_accessors. In all other cases, using @name over self.name will violate encapsulation and give yourself a headache. You gave the exact reason in your question — if there is extra logic in the getter/setter, you must duplicate it if you access the instance variable directly.