Question

Im reading the Rails guides for Rails 3 and they use this method:

cattr_accessor :attribute

What is this method? Is it a Rails method? I’ve never seen it before.

Answer 1

It is a rails thing. Basically like the attr_* methods, but for the class level. One thing you wouldn’t expect is because it uses a backing @@ variable, the value shared between the class and all instances.

class Foo
  cattr_accessor :bar
end
# => [:bar] 
foo1 = Foo.new
# => #<Foo:0x4874d90> 
foo2 = Foo.new
# => #<Foo:0x4871d48> 
foo1.bar = 'set from instance'
# => "set from instance" 
foo2.bar
# => "set from instance" 
Foo.bar
# => "set from instance"