OOP.bit

package:application/vnd.bitty-archive;
data:text/json;count=139;path=info.json;
{
  "id": 0,
  "title": "Basics/06. OOP",
  "description": "",
  "author": "Tony",
  "version": "1.0",
  "genre": "TUTORIAL",
  "url": ""
}
data:text/lua;count=747;path=class.lua;
--[[
Example for the Bitty Engine

Copyright (C) 2020 - 2024 Tony Wang, all rights reserved

Homepage: https://paladin-t.github.io/bitty/
]]

-- Declares a class.
function class(kls, base)
	if not base then
		base = { }
	end

	kls.new = function (...)
		local obj = { }
		setmetatable(obj, kls)
		if obj.ctor then -- `ctor` is short for "constructor", where you can initialize your instance.
			obj:ctor(...)
		end

		return obj
	end

	kls.__index = kls

	setmetatable(kls, base)

	return kls
end

-- Determines whether an object is instance of a specific class.
function is(obj, kls)
	if kls == nil then
		error('Invalid class.')
	end

	repeat
		if obj == kls then
			return true
		end
		obj = getmetatable(obj)
	until not obj

	return false
end

data:text/lua;count=758;path=main.lua;
--[[
Example for the Bitty Engine

Copyright (C) 2020 - 2024 Tony Wang, all rights reserved

Homepage: https://paladin-t.github.io/bitty/
]]

require 'class'

A = class({
	ctor = function (self, n)
		print('A:ctor')

		self.n = n
	end,

	fun = function (self)
		print('A:fun')

		return self.n
	end
})

B = class({
	ctor = function (self, n)
		A.ctor(self, n)
		print('B:ctor')
	end
}, A)

C = class({
	ctor = function (self, n)
		print('C:ctor')

		self.n = n
	end,

	fun = function (self)
		print('C:fun')

		return self.n
	end
})

local a = A.new(1)
local b = B.new(2)
local c = C.new(3)

print(a:fun())
print(b:fun())
print(c:fun())

print('a is A: ' .. tostring(is(a, A)))
print('b is A: ' .. tostring(is(b, A)))
print('c is A: ' .. tostring(is(c, A)))