class Class

# File lib/clean-annotations/class_attribute.rb, line 4
def class_attribute name, default=nil, &block
  raise ArgumentError.new('name must be symbol') unless name.is_a?(Symbol)

  ivar = "@class_attribute_#{name}"

  instance_variable_set ivar, block || default

  define_singleton_method('%s=' % name) { |arg| send(name, arg) }
  define_singleton_method(name) do |arg=:_undefined, &block|
    # define and set if argument given
    if block || arg != :_undefined
      return instance_variable_set ivar, block || arg
    end

    # find value and return
    ancestors.each do |klass|
      if klass.instance_variable_defined?(ivar)
        value = klass.instance_variable_get ivar
        return value.is_a?(Proc) ? instance_exec(&value) : value
      end
    end
  end
end