Virtual function dispatch for Resources not working

[mio991]

If I have a CustomResource like this:

#[derive(GodotClass)]
#[class(init, base=Resource)]
pub struct BaseResource {
    _base: Base<Resource>,
}

#[godot_api]
impl BaseResource {
    #[func(virtual, rename = _get_value)]
    pub fn get_value(&self) -> GString {
        unimplemented!("get_value should be overridden");
    }
}

and extend it into an actual implementation like this:

extends BaseResource
class_name TestResource

func _get_value() -> String:
	return "Lila"

I get an Unimplemented Error, if I try to call get_value() from rust like so:

impl BaseResource {
    pub fn test_virtual(&self) {
        godot_print!("Value: {}", self.get_value());
    }
}

Reproduction Steps

1. decrompress demo.zip
2. add Godot 4.3-dev6 in the ./bin folder
3. build the rust library
4. start Godot 4.3-dev6
5. open the Project under ./godot
6. execute main.tscn
7. click the Test-Button

There are Exceptions in the Output.

Expected Behaviour

I expect a console output of Value: Lila.

[Bromeon]

Can you please describe the problem in a minimal complete example here, so users don't need to download a ZIP package? Thanks!

[mio991]

I edited my initial Comment, I hope that helps. I can also push the demo project from the zip file t github if you want.

[Bromeon]

I meant http://www.sscce.org, i.e. a small code example that is enough to demonstrate the problem, focuses only on the problem and removes anything that's not absolutely necessary. But it's still self-contained, so others can quickly test it, without the need to download + compile + load the whole project. If Godot scenes are necessary to reproduce the issue, you can either set them up in code or describe how they look in some comments.

Don't get me wrong, the .zip can still be useful, but it should be an addition to the actual problem description. It must be possible to understand and discuss the issue without download.

Thanks for your understanding! 🙂

[lilizoey]

I think if you want virtual methods like this to work you'll have to call them like

self.base().call("test_virtual".into(), &[]);

because otherwise you'll just end up calling the rust function.

maybe we should change this so that the godot_api macro automatically overwrites the original rust function to do something like the call above?