Ruby類繼承：如何防止公共方法在子類中被覆蓋

Question

是否可以防止公共方法被子類覆蓋？

class Parent
  def some_method
     #important stuff that should never be overwritten
  end
end

class Child < Parent
  def some_method
     #should not be possible to overwrite (raise an error if a child class tries to do it)
  end
end

謝謝！

Answer 1

您可以使用'method_added'和'inherited'鈎子來實現此目的：

class Foo
  def self.inherited(sub)
    sub.class_eval do
      def self.method_added(name)
        if name == :some_method
          remove_method name
          raise Exception, "Can't override #{name} method"
        end
      end
    end
  end
end

class Bar < Foo
end

class Bar
  def some_method
  end
end
# => Exception: Can't override some_method method