class interface P_SEPARATED_STRING
creation
   make (a_separator: STRING)
      --  Make separated string with specified separator.
      require
         not_void: a_separator /= Void
   make_space
      --  Make string separated by a single string.
feature(s) from P_SEPARATED_STRING
   --  Operation(s)
   add (a_string: STRING)
      --  Add a string (and separator if necessary).
      require
         not_void: a_string /= Void
   reset
      --  Reset.
feature(s) from P_SEPARATED_STRING
   --  Access
   as_string: STRING
invariant
   separator_not_void: separator /= Void;
   as_string_not_void: as_string /= Void;
end of P_SEPARATED_STRING