>>>>> "D" == Dave Thomas <Dave / PragmaticProgrammer.com> writes:

D> subclasses of String get treated as if they were strings. When a

  yes, ruby check TYPE(obj) == T_STRING

D> string is used as a hash key, it is copied automatically, so that
D> subsequent changes to the string don't affect the hash.

 copy-on-write, like regexp


Guy Decoux