Two different instance of the same script?

Questions
#1

i have a physic.lua script and i want to use it in player and enemy game object.
so, i wrote te next line in they controller script

local physics = require ("path")

but the problem is that i overwrite the local variables in physics.lua.

-- in player script
local pyshics1 = require("path")
physics1.a = 1
-- in enemy script
local pyshics2 = require("path")
physics2.a = 2

--then when i want to get the value i got something like this
-- in player script
physics1.get_a() -- Value : 2
-- in enemy script
physics2.get_a() -- Value: 2

in java i would solve it using something like this

-- in player 
Physics physics1= new Physics();
physic1.set_a(1);
-- in enemy 
Physycs  physics2 = new Physics();
physic.2_set_a(2)

--then
-- in player 
physics1.get_a() -- Value: 1
-- in enemy 
physics2.get_a() -- Value: 2

so, how can i do that ? two diferent instance of the same script ?

#2

Edit: Sorry, I missunderstood your use case, the below post might not apply 100% to you.

The two script instances, while still sharing the same code, will have two different self instances in those scripts.

One approach is to use script properties to set specific properties on scripts that are shared/reused.

For example, in the first lines of your script you could write something like this:

go.property("is_enemy", false)

Then in the script functions, this property is available on the self object, like this:

function init(self)
	if self.is_enemy then
		-- this script instance is used by an enemy
	else
		-- this is not an enemy, do something else
	end
...

Script properties can be changed/set when gameobjects are they are spawned from factories, but also directly in the editor, for example:

image

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#3

A more correct answer to your use case: :slight_smile:

Worth noting is that this is close to doing object oriented programming in Lua. Depending on what your goal is, it might make sense to actually taking a look at my first answer, maybe some of the features Defold exposes natively (especially script properties) can be used instead?

But if I would make something like you are asking for, I would make physics.lua actually return a constructor function that will return a new “physics instance”. Something like this:

-- physics.lua

local function physics_constructor()
    local new_instance = {
        a = 0
        b = 0
    }

    new_instance.set_a = function(self, new_value)
        self.a = new_value
    end

    new_instance.get_a = function(self)
        return self.a
    end

    return new_instance
end

return physics_constructor

And when using in your different scripts;

-- player.script
local physics_constructor = require("path_to_physics.lua")
function init(self)
    self.physics_instance = physics_constructor()
    self.physics_instance:set_a(1)
    self.physics_instance.b = 1

    print(self.physics_instance:get_a(), self.physics_instance.b)
    -- -> 1   1
end

...

-- enemy.script
local physics_constructor = require("path_to_physics.lua")
function init(self)
    self.physics_instance = physics_constructor()
    self.physics_instance:set_a(2)
    self.physics_instance.b = 2

    print(self.physics_instance:get_a(), self.physics_instance.b)
    -- -> 2    2
end
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