gistfile1.ex

defmodule HealthComponent do
    use GenEvent

    ### Public API
    def get_hp(entity) do
        :gen_event.call(entity, HealthComponent, :get_hp)
    end

    def alive?(entity) do
        :gen_event.call(entity, HealthComponent, :alive?)
    end
    
    ### GenEvent API
    def init(hp) do
        {:ok, hp}
    end

    def handle_call(:get_hp, hp) do
        {:ok, hp, hp}
    end

    def handle_call(:alive?, hp) do
        {:ok, hp > 0, hp}
    end

    def handle_event({:hit, amount}, hp) do
        {:ok, hp - amount}
    end

    def handle_event({:heal, amount}, hp) do
        {:ok, hp + amount}
    end
end