jumpsplat120 / extended_types

More powerful Lua types.

extended_types

More powerful Lua types.

A patch for the builtin type function for lua. Simply put, this type function attempts to checks for the existence of a .type or .__type value or function. This avoids conflicts with standard lua types, but allows tables to opt-in to being treated like a new type. Since it can be a value OR function, the return values can be anything, but the general usage is to ultimately return a string.

Order of operations is as follows:

• If it's not userdata or a table, then return the type. This handles standard lua types.
• If it's userdata, then we check for a type method, and return the return value of said method. This handles LÖVE2D types.
• If it's a table, we check for a __type metavalue or metafunction. If it's a function, we return the value got from running the function, otherwise, we just return whatever the value was.

The following example uses Classy and LÖVE2D to show how you might do such a thing.

Classy

local Object, Point, p

Object = require("Classy")
Point = Object:extend()

function Point:new(x, y)
    self.x = x or 0
    self.y = y or 0
end

Point.__type = "point"

p = Point(10, 20)

print(type(p)) -- "table"

require("extended_types")

print(type(p)) -- "point"

LÖVE2D

local img = love.graphics.newImage("test.png")

print(type(img)) -- "userdata"

require("extended_types")

print(type(img)) -- "point"