Lua class objects?

Question

I'm new to Lua and I'm wondering if there's a way to make many class objects to make different items in my case like in a OOP language like C# or Java. An example of what I'm saying is a class like this in Lua...

weapon = {}

function weapon.load()
{
    weapon.name = "CHASE'S BUG"
    weapon.damage = 1
    weapon.rare = "Diet Valley Cheez"
    weapon.hottexture = love.graphics.newImage("/ledata/invalid.png")
    weapong.playtexture = love.graphics.newImage("/ledata/invalid.png")
    weapon.dura = 1
    weapon.type = "swing"
}

But in a main class you could make new objects of that class which would be done like so in something like C#

weapon Dagger = new weapon();
Dagger.name = "Dagger of Some Mountain"
...

Is there a way to do that in Lua?

Huy Le · Answer 1 · 2013-08-23T07:35:30.883

2

There're many ways. This is a simple one. Not really much OOP, you don't have inheritance and some other stuff. But I think this will work in your case.

function weaponFire ()
    print "BANG BANG"
end

function newWeapon (opts)
    local weaponInstance = {}

    weaponInstance.name = opts.name
    weaponInstance.damage = opts.damage

    weapon.fire = weaponFire

    return weaponInstance
end

edited Aug 23 '13 at 07:35

answered Aug 23 '13 at 06:34

Huy Le

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score 2 · Answer 2 · answered Sep 15 '13 at 05:50

Another way to go about it is to use a table like so (using the example of a car):

    Car = {}
    Car.new = function(miles,gas,health)
        local self = {}

        self.miles = miles or 0
        self.gas = gas or 0
        self.health = health or 100

        self.repair = function(amt)
            self.health = self.health + amt
            if self.health > 100 then self.health = 100 end
        end

        self.damage = function(amt)
            self.health = self.health - amt
            if self.health < 0 then self.health = 0 end
        end

        return self
    end

It creates a table called 'Car' which would be the equivalent of a class, not an instance, then it defines a method "new" in the Car class which returns an instance of a car with variables and functions. An example to using this implementation:

    local myCar = Car.new()
    print(myCar.health)
    myCar.damage(148)
    print(myCar.health)
    myCar.repair(42)
    print(myCar.health)

score 1 · Accepted Answer · answered Aug 23 '13 at 06:36

1

Lua is object oriented, but it's not like Java/C++/C#/Ruby, etc, there's no native class, the only way to create new object is to clone an existing object. That's why it's called prototype language(like JavaScript).

Read Programming in Lua Chapter 16. You can mock normal OOP using metatable.

answered Aug 23 '13 at 06:36

Yu Hao

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@freemann098 Yes, you can, Lua provides the tool to make tools, you need some work though. Read the book, that's the book every Lua programmer should read. – Yu Hao Aug 23 '13 at 06:45
I would suggest also [MiddleClass](https://github.com/kikito/middleclass): it's a library implementing Object-Orientation for Lua. – Giovanni Cappellotto Aug 23 '13 at 09:51

xpol · Answer 4 · 2013-08-25T11:53:13.300

0

since you tagged with love2d, you may have a look at middleclass. It have docs there. And more it have addon like stateful which is mainly for game and love2d.

edited Aug 25 '13 at 11:53

answered Aug 25 '13 at 11:29

xpol

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Lua class objects?

4 Answers4