Question

I thought it was possible to define attr_accessor methods in a eigenclass like this:

class IOS
  @@modules_paths = "hello"

  class << self
    attr_accessor :modules_paths
  end

end

puts IOS::modules_paths

But this returns nothing.

Is there a way to do it?

Answer 1

The attr_accessor you add to the class uses class-level instance variables, not class variables. This can actually be more helpful in some cases, since class variables can get ridiculous when inheritance enters the picture.

class IOS
  @modules_paths = "hello"

  class << self
    attr_accessor :modules_paths
  end
end

puts IOS::modules_paths # outputs "hello"

If you really need it to use class variables, you can define the methods manually, pull in ActiveSupport and use cattr_accessor, or just copy the relevant ActiveSupport methods.