+# This file is part of NIT ( http://www.nitlanguage.org ).
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# COmbat interactions between characters.
+module combat
+
+import character
+
+# Something that can be used to attack someone and inflict damage.
+interface Weapon
+ # Damage per second inflicted by this weapon.
+ fun dps: Float is abstract
+end
+
+# Something that can be combatted, it can `attack` and `defend`.
+#
+# World items can also be `Combatable`.
+# `defend` method is then used to determines how the object react to an attack
+# Some magical items can even `attack`.
+interface Combatable
+ fun hit_points: Int is abstract
+
+ # A `Combatable` can attack a `target` that is also a `Combatable`.
+ #
+ # Attack the `target` using `wepaon` and returns the number of inflicted hit points.
+ fun attack(target: Combatable, weapon: Weapon): Int is abstract
+
+ # Like `attack` but cannot be defended.
+ fun direct_attack(target: Combatable, weapon: Weapon): Int is abstract
+
+ # `Combatable` can defend against attacks.
+ #
+ # Defends against a number of received hit points and return the number of pared hit points.
+ #
+ # @param hit: damage received.
+ fun defend(hit: Int): Int is abstract
+
+ # Is the character still have hit_points?
+ fun is_dead: Bool do return hit_points > 0
+end
+
+# Characters are now `Comabatable`
+redef class Character
+ super Combatable
+
+ # Use character `health` to determines hit_points.
+ redef fun hit_points do return health
+end
+
+# Dwarves can be used as weapons.
+redef class Dwarf
+ super Weapon
+
+ # Dwarf `dps` are based on the dwarf `base_endurance` (represents weight here)
+ redef fun dps do return base_endurance.to_f / 10.0
+end