Add classtoi-light

classtoi-light.lua

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+--- Reuh's light class library version 0.1.0. Lua 5.1-5.3 and LuaJIT compatible.
+-- Lighter and faster version of classtoi, keeping the same syntax but with uncommon features removed.
+-- Features:
+-- * class creation and inheritance with class(table...) or subclass(table...) (left-to-right priority). Parent classes are shallowly copied on creation in the new class.
+-- * instance creation with class:new, which calls the :init constructor (which can returns another object instead of the automaticaly created one)
+-- * every methamethod supported in instances except __index
+-- * a default :is method to check if an object is an instance of a class (ignore parents): class:is(obj) or obj:is(class) returns true if obj is of class
+-- * a default __tostring method and __name attribute for pretty printing of objects and classes
+-- Main differences from classtoi:
+-- * methamethods are only applied to instances and not classes
+-- * can't redefine __init
+-- * instance constructor is renamed to :init
+-- * inherited fields and methods are copied on creation; adding a new field to a parent class after creation will not affect child classes
+-- * is can only be called in its class:is(object) or object:is(class) form (returns true if object is of class), and ignore parents
+-- * no class commons support
+-- Please note that if you redefine :new or :is, they will be used instead of the class default.
+
+local newClass, class_mt
+newClass = function(...)
+	local class = {}
+	for _, mixin in ipairs({...}) do
+		for k, v in pairs(mixin) do
+			class[k] = v
+		end
+	end
+	class.__index = class
+	return setmetatable(class, class_mt)
+end
+class_mt = {
+	new = function(self, ...)
+		local obj = setmetatable({}, self)
+		return obj.init and obj:init(...) or obj
+	end,
+	is = function(self, other)
+		if getmetatable(self) == class_mt then -- class:is(obj)
+			return getmetatable(other) == self
+		else -- obj:is(class)
+			return getmetatable(self) == other
+		end
+	end,
+	__call = newClass,
+	__tostring = function(self)
+		local mt = getmetatable(self)
+		setmetatable(self, nil)
+		local str = tostring(self)
+		setmetatable(self, mt)
+		return str:gsub("^table", "class")
+	end
+}
+class_mt.__index = class_mt
+
+-- base class
+return newClass {
+	__name = "object",
+	__tostring = function(self)
+		local mt = getmetatable(self)
+		setmetatable(self, nil)
+		local str = tostring(self)
+		setmetatable(self, mt)
+		return str:gsub("^table", self.__name)
+	end
+}