How to add a scene and how to create an instance of a class?

[whileload]

local init_game = {
	extends = Node2D,
}
function init_game:_ready()
	local t = Node2D:new()
	self.add_child(t)
end
return init_game

Why doesn't this work or how to do it right?

I created my custom node.
How do I initialize it in another script?

[gilzoide]

Hey @whileload, thanks for the question.

Why doesn't this work or how to do it right?

Have you looked at the error messages? They probably have a hint on what's the problem and where it happens, at least in which line of your script.

[whileload]

Привет, @whileload, спасибо за вопрос.

Почему это не работает или как сделать правильно?

Вы смотрели сообщения об ошибках? В них, вероятно, содержится подсказка о том, в чём проблема и где она возникает, по крайней мере, в какой строке вашего скрипта.

E 0:00:02:404   luagdextension::to_variant: add_child
  <Исходный код C++>src\utils\convert_godot_lua.cpp:127 @ luagdextension::to_variant()

[gilzoide]

Yeah, ok, this error message is not useful at all, sorry about that.
In this case, the problem is likely the attempt to call add_child using . instead of Lua's method notation with ::

-- self.add_child(t)
self:add_child(t)

[whileload]

Да, хорошо, это сообщение об ошибке совершенно бесполезно, извините. В данном случае проблема, скорее всего, заключается в попытке вызвать add_child с помощью . вместо обозначения метода в Lua с помощью ::

self--
 self.add_child(t):add_child(t)

Thanks a lot, now I've realized my stupid mistake.

The second question is, how do I create an instance of a new class from another class?

local MyClass = {
	extends = Node2D,
	class_name = "MyClass",
}
return MyClass

How do I create a class?

local init_game = {
	extends = Node2D,
}
function init_game:_ready()
	-- not work
	local t = MyClass:new()
	self:add_child(t)
end
return init_game

[gilzoide]

The second question is, how do I create an instance of a new class from another class?

Specifying the class_name should be working, but it seems to not be working at all. That's a bug, I'll try fixing that later.
In any case, you can load the LuaScript using ResourceLoader and use it instead:

local init_game = {
	extends = Node2D,
}

-- Here's the loading part.
-- This is just like using GDScript's `load` function
local MyClass = ResourceLoader:load("res://MyClass.lua")

function init_game:_ready()
	-- Now it should be working
	local t = MyClass:new()
	self:add_child(t)
end
return init_game