batteries/class.lua

57 lines
1.2 KiB
Lua

--[[
barebones oop basics
supports basic inheritance and means you don't have to build/set your own metatable each time
todo: collect some stats on classes/optional global class registry
]]
local function class(inherits)
local c = {}
c.__mt = {
__index = c,
}
setmetatable(c, {
--wire up call as ctor
__call = function(self, ...)
return self:new(...)
end,
--handle single inheritence
__index = inherits,
})
--common class functions
--internal initialisation
--sets up an initialised object with a default value table
--performing a super construction if necessary and assigning the right metatable
function c:init(t, ...)
if inherits and inherits.new then
--construct superclass instance, then overlay args table
local ct = inherits:new(...)
for k,v in pairs(t) do
ct[k] = v
end
t = ct
end
--upgrade to this class and return
return setmetatable(t, self.__mt)
end
--constructor
--generally to be overridden
function c:new()
return self:init({})
end
--get the inherited class for super calls if/as needed
--allows overrides that still refer to superclass behaviour
function c:super()
return inherits
end
--done
return c
end
return class