Addison-Wesley Professional Ruby Series Writing Efficient Ruby Code

Chapter . Patterns

Instance Variables versus Accessors

As described earlier, method calls in Ruby usually involve a method lookup in a hash structure, which is considerably more expensive than a simple machine-supported subroutine call in statically compiled languages. We therefore want to avoid method calls as much as possible.

Accesses to class/module attributes declared via attr_accessor, attr_reader, or attr_writer all involve method calls. We can reduce the overhead of attribute access by using the corresponding instance variables directly. So, instead of attribute, we’d write @attribute. And instead of

self.attribute = expr

we’d write

@attribute = expr

which results in shorter code as well.

Obviously, this transformation breaks encapsulation and ...