module ClassProp::MustDefine
This module itself does not do anything. If you set a class property to ClassProp::MustDefine
then subclasses must define that property. For example, the following code raise an exception.
class Base include ClassProp define_class_prop 'independent' self.independent = ClassProp::MustDefine end class X1 < Base end X1.independent # raises exception 'must-define-class-property: independent'