variable in other scene is returning nil even when set

[TrainzMarcel]

so i have two scenes;
"basevehicle" and "suspensionarm" (child of spatial named "wheels" which is a child of basevehicle)

in suspensionarm.lua, im only putting data (variables)
and in basevehicle.lua im putting all the logic

under basevehicle i put a node named "wheels" to contain the suspensionarms

when i try to assign a node to v.ray (declared as suspensionarm.ray = nil in its script or not) it still prints nil, why is this happening?

[gilzoide]

Hey @TrainzMarcel.
Well, setting something to nil in Lua is the same as deleting it from the table. So to declare an Object property with default value of null, you should use suspensionarm.ray = Object.null. This would declare a property in the script's manifest, so it could be accessed by GDScript or by Godot Objects in Lua via get/get_indexed/set/set_indexed.

Now, if you had the Lua script instance that is attached to the Object instead of the Object itself, it wouldn't matter if the property was declared or not to Godot and you would be able to set/get it without any fuzz, Lua table style. You can get the Lua script instance today by using GD.get_lua_instance(v). But now that I'm thinking of it, in Lua we probably always want to have the Lua script instance and not the script owner, which is a raw Godot Object pointer 🤔

Ok, so for now, either declare the property using Object.null instead of nil, or use GD.get_lua_instance(some_object) to work with the Lua script instance instead of the Object pointer.
But in a future release (possibly the next one), I guess we should always unbox the Lua script instance from Object Variants automatically. Sounds like a much better developer experience to me ^^

Thanks for the insight!

[TrainzMarcel]

thanks!! im happy i can continue working on my data driven approach

[TrainzMarcel]

also, i think i would prefer if u shifted ur focus to making lua work in gdextension, since godot 4.0 is the hot new thing (no pressure)

[gilzoide]

also, i think i would prefer if u shifted ur focus to making lua work in gdextension, since godot 4.0 is the hot new thing (no pressure)

Well, I guess you're right. Thanks for the encouragement ^^

[gilzoide]

Oh, also, next time you could paste your code using code blocks instead of posting an image. This is useful so that people could copy/paste the code to test it out.

You use triple backticks (```) + language name to start a syntax-colored code block (like: ```lua). Then another triple backticks to end the block.

It appears like this:

-- This will appear as lua code
local msg = "Hello Lua"
print(msg)

[TrainzMarcel]

will do

[gilzoide]

FYI, I created issue #47 regarding automatic unboxing of Lua script instances.