Inheritance

Class uses __includes to copy behavior from one or more classes or tables. Included classes are also tracked as parents for Class:is and instance:Is checks.

Single include

local Named = Class({
	__type = "Named",

	getName = function(self)
		return self.name
	end,
})

local Player = Class({
	__type = "Player",
	__includes = Named,

	init = function(self, name)
		self.name = name
	end,
})

local player = Player("Ada")

print(player:getName())
print(player:Is(Player))
print(player:Is(Named))

Multiple includes

local CanFly = Class({
	__type = "CanFly",

	fly = function()
		return "flying"
	end,
})

local CanSwim = Class({
	__type = "CanSwim",

	swim = function()
		return "swimming"
	end,
})

local Duck = Class({
	__type = "Duck",
	__includes = { CanFly, CanSwim },
})

local duck = Duck()

print(duck:fly())
print(duck:swim())
print(duck:Is(CanFly))
print(duck:Is(CanSwim))

Includes are applied in order. Existing keys on the target class are preserved. If two included tables define the same key, the first included value is kept. The class definition itself has priority over included values.

Transitive parents

Parent links are transitive. If Dog includes Animal, and Animal includes Entity, then Dog() is recognized as Dog, Animal, and Entity.

local Entity = Class({
	__type = "Entity",
})

local Animal = Class({
	__type = "Animal",
	__includes = Entity,
})

local Dog = Class({
	__type = "Dog",
	__includes = Animal,
})

local dog = Dog()

print(Class:is(dog, Dog))
print(Class:is(dog, Animal))
print(Class:is(dog, Entity))

Global string include

String includes are resolved through _G.

_G.SharedBehavior = {
	shared = function()
		return true
	end,
}

local Example = Class({
	__includes = "SharedBehavior",
})

When a string include resolves to a table, it is copied and tracked like any other included table.