note
   description:
      "Generic enumeration"
   copyright:
      "[
               Copyright (C) 2008-2017: Paolo Redaelli

               This library is free software; you can redistribute it and/or
               modify it under the terms of the GNU Lesser General Public License
               as published by the Free Software Foundation; either version 2.1 of
               the License, or (at your option) any later version.

               This library is distributed in the hope that it will be useful, but
               WITHOUT ANY WARRANTY; without even the implied warranty of
               MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
               Lesser General Public License for more details.

               You should have received a copy of the GNU Lesser General Public
               License along with this library; if not, write to the Free Software
               Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
               02110-1301 USA
         ]"
deferred class ENUM
   -- A wrapper for an enumeration

insert
   ANY
      undefine default_create
      end

feature {ANY}
   is_valid_state: BOOLEAN
         -- Is the value of the enumeration valid?
      do
         Result := is_valid_value(value)
      end

feature {WRAPPER_HANDLER}
   value: INTEGER
      -- The current value of the enumeration.

   set, change_value (a_value: INTEGER)
      require
         is_valid_value(a_value)
      do
         value := a_value
      end

   is_valid_value (a_value: INTEGER): BOOLEAN
         -- Can `a_value' be used in a `set_value' feature call?
      deferred
      end

invariant
   is_valid_state

end -- class ENUM