base.md

knife.base

A base class for class-based OOP.

Example usage

Require the library.

local Base = require 'knife.base'

Call Base:extend() to create a new class.

local Thing = Base:extend()

Call extend on your classes to create new subclasses.

local Bullet = Thing:extend()

Give your classes default properties.

local Barrel = Thing:extend({ explosionRadius = 10 })
-- or
local Barrel = Thing:extend()
Barrel.explosionRadius = 10

Define constructors for your classes.

function Barrel:constructor (radius)
    self.explosionRadius = radius
end

Create methods on your classes.

function Barrel:explode ()
    Game:spawnExplosion(self.explosionRadius)
end

Instantiate your classes.

local barrel = Barrel(500)
barrel:explode()

Caveats/features

• All classes extend the base class. The base class has only two members, extend and constructor.

• All class members are visible to both the class and the instance -- there is no separation between 'static' and 'instance' scopes. It's up to the user to document and use members appropriately.

  Because of this, object:extend() will create a subclass of an object, which can be instantiated. This is probably not useful.

• Just for kicks, any return values from the constructor come back as return values when instantiating a class, after the instance itself.