I just stumbled on this bit of ruby code from a long time ago. Matt Knox and I were trying to solve the question of "can you selectively prevent monkey-patching in ruby?" I think this is the best we could do at the time.

cantTouchThis.rb

# Ever get tired of people messing with your ruby classes?
# now you can put the hammer down and stop them. Just 
# include this module and no one will be able to modify the 
# class implementation or any instance implementations.


module Stop
  module CantTouchThis
    def self.included(mod)

      %w[instance_variable_get instance_variable_set].each do |m|
        send(:protected, m)
      end

      eigenclass = class << mod; self; end
      %w[const_set class_variable_get class_variable_set public_class_method attr attr_reader attr_writer].each do |m|
        eigenclass.send(:protected, m)
      end

      mod.send(:define_method, :instance_eval) do
        raise NoMethodError, "do do do, uh uh, duh duh. can't touch this"
      end

      %w[class_eval class_exec module_eval module_exec include extend alias_method unfreeze remove_const remove_method undef_method define_method].each do |m|
        mod.class.send(:define_method, m) do
          raise NoMethodError, "do do do, uh uh, duh duh. can't touch this"
        end
      end

      mod.send(:protected, :send)
      eigenclass.send(:protected, :send)
      mod.freeze
    end
  end
end

# simplest possible testing framework
def r
  yield
  puts "fail"
rescue => e
  p e
end

# some simple tests

module B
  def self.included(_)
    puts "fail"
  end
end

class A
  include Stop::CantTouchThis
  r{class_eval ''            }
  r{class_exec  {}           }
  r{module_eval ''           }
  r{include B                }
  r{extend  B                }
  r{alias_method :class, :id }
  r{define_method(:foo) {}   }
  r{ remove_const(:FOO)      }
  r{ remove_method(:id)      }
end


r{ A.new.instance_eval ''                   }
r{ A.new.instance_variable_get(:@foo)       }
r{ A.new.instance_variable_set(:@foo, :foo) }
r{ A.class_variable_get(:@foo)              }
r{ A.new.class_variable_get(:@foo)          }
r{ A.class_variable_set(:@foo, :bar)        }
r{ A.new.class_variable_set(:@foo, :bar)    }
r{ A.const_set(:B, :foo)                    }
r{ A.public_class_method(:send)             }
r{ A.const_set(:FOO, :bar)                  }
r{ A.attr(:foo)                             }
r{ A.attr_reader(:foo)                      }
r{ A.attr_writer(:foo)                      }
r{ A.new.send(:id)}
r{ A.send(:id)}