ECS/Component.lua

--[[
    ECS Component class
    @author : Eiyeron Fulmincendii

    A component is a data container for entities. It determines also which systems the holder entity
    will be processed on.
]]--
local class = require("class")
local object = require("object")
local __cid = 0

local component = class(object)

local function eq(a, b) return a.__cid == b.__cid end
local function le(a, b) return a.__cid <= b.__cid end
local function lt(a, b) return a.__cid < b.__cid end

local function make_component(...)
    local c = class(component, ...)
    __cid = __cid + 1
    -- Component unique ID. If you don't want to break everything, avoid touching this.
    c.__cid = __cid
    -- Override this variable at class creation to have a more explicit tostring result.
    c.__name = "Component"
    -- Used in SystemFilters
    c.__lt = lt
    c.__le = le
    c.__eq = eq

    local mt = getmetatable(c)
    -- Used in SystemFilters
    mt.__lt = lt
    mt.__le = le
    mt.__eq = eq
    -- Class type functions.
    mt.__tostring = function(a) return string.format("{Component class %s (id:%d)}", a.__name, a.__cid) end
    return c
end


return make_component