Ruby

TracePoint.new(:c_call) { |tp| if tp.method_id == :const_missing puts "top-level const_missing is #{tp.self}'s" end }.enable { Foo rescue 1 } # => top-level const_missing is Object's module M refine Object.singleton_class do def const_missing c 'Explicit invocation works.' end def new 'Can refine other singleton methods.' end end end using M puts Object.const_missing :Foo # => Explicit invocation works. Foo rescue p $! # => #<NameError: uninitialized constant Foo> def Object.const_missing c 'So does direct definition.' end puts Foo # => So does direct definition. puts Object.new # => Can refine other singleton methods. 

Is it a bug?