Inheritance Issue - SuperClass object cannot be converted to SubClass

[riccardostokker]

Hello everyone!
I've just started to use PyO3 for a library that I am developing. I want to define a ThinFilmResistor class that is extending a Component class. This is the code I wrote in order to achieve this:

#[pyclass(subclass, name = "Component")]
pub struct ComponentWrapper {
    pub component: Box<dyn CloneableComponent>,
}

#[pymethods]
impl ComponentWrapper {

    fn __repr__(&self) -> String {
        format!("Component: {}", self.component.get_designator())
    }

    fn __str__(&self) -> String {
        format!("Component: {}", self.component.get_designator())
    }

}

// Thin Film Resistor
#[pyclass(extends=ComponentWrapper, name = "ThinFilmResistor")]
pub struct ThinFilmResistorWrapper {
}

#[pymethods]
impl ThinFilmResistorWrapper {
    #[new]
    fn new(designator: String, value: f64) -> PyClassInitializer<Self> {
      [...]
    }

    fn __init__(mut self_: PyRefMut<'_, Self>, designator: String, value: f64) {
        self_.as_super().component = Box::new(ThinFilmResistor::new(designator, value));
    }

    fn __repr__(self_: PyRef<'_, Self>) -> String {
        format!("ThinFilmResistor: {}", self_.as_super().component.get_designator())
    }

    fn __str__(self_: PyRef<'_, Self>) -> String {
        format!("ThinFilmResistor: {}", self_.as_super().component.get_designator())
    }

}

I get the following error message, and the __str__ and __repr__ methods also do not seem to be working since the class is being printed as <builtins.ThinFilmResistor object at 0x0000021E1BBEDCF0>

Traceback (most recent call last):
  File x line 25, in <module>
    circuit.add_component(resistor)
TypeError: argument 'component': 'ThinFilmResistor' object cannot be converted to 'Component'

Any help is greatly appreciated!
Riccardo

[birkenfeld]

What do you mean by __str__ and __repr__ not working? They will be taken from the subclass definition if the object is of type ThinFilmResistor, so that's as expected.

I'm not sure why taking a Component argument doesn't work here. Can you try taking it as Bound<PyAny> and then call downcast::<Component>?