how can I keep a PyAny pointer in rust pyclass

[shenjackyuanjie]

pub mod camera {
    use pyo3::prelude::*;

    #[pyclass(name = "Camera_rs")]
    pub struct CameraRs{
        pub dx: f64,
        pub dy: f64,
        #[pyo3(get, set)]
        pub zoom: f64,
        #[pyo3(get, set)]
        pub max_zoom: f64,
        #[pyo3(get, set)]
        pub min_zoom: f64,
        pub window: &PyAny,
    }

    #[pymethods]
    impl CameraRs {
        #[new]
        fn py_new(dx: f64, dy: f64, window: &PyAny) -> PyResult<Self> {
            return Ok(CameraRs {dx,
                                dy,
                                zoom: 1 as f64,
                                min_zoom: 1 as f64,
                                max_zoom: 1 as f64,
                                window})
        }

        fn __enter__(&self) -> PyResult<()> {
            println!("I enter!");
            return Ok(())
        }

        #[allow(unused_variables)]
        fn __exit__(&self, exception_type: &PyAny, exception_value: &PyAny, traceback: &PyAny) -> PyResult<()> {
            println!("I exit!");
            return Ok(())
        }
        
    }

}

I want to keep a window pointer in my pyclass, but rustc tells me I can't

[birkenfeld]

It needs to be Py<PyAny>. This section of the guide may be helpful to understand the difference.

In short: &'py PyAny is only valid to use as long as you hold the Python Interpreter Lock (GIL). Therefore it is not safe to put into a pyclass, which can live indefinitely as a Python object. Py<PyAny> requires a Python GIL token to access and is therefore safe to share around.

[birkenfeld]

To clarify, you want to call self.start() in Rust instead?

My example probably wasn't the best - it uses py_self: Py<Self> in order to save the marshaling to self and back when only returning self again. When you actually need Rust's self, you can just take it like in other pymethods:

fn __enter__(&self) -> PyResult<Self> {  // or &mut self
    self.start(...)?;
    Ok(self)
}

[shenjackyuanjie]

hmmmmm
rustc and rust plugin tells me I need to return self not &self

[shenjackyuanjie]

[birkenfeld]

Yeah sorry, that was not thought through.

Better to do stay with PyRef, since it de-references automatically to Self:

    fn __enter__(slf: PyRef<Self>) -> PyResult<PyRef<Self>> {
        slf.start()?;
        Ok(slf)
    }

[shenjackyuanjie]

ok! that work! super thanks!