How can I returns an instance of child class in instance methods

[bachue]

for example:

#[pymethods]
impl CredentialProvider {
    #[args(opts = "GetOptions::default()")]
    #[pyo3(text_signature = "($self, opts)")]
    fn get(&self, opts: GetOptions) -> PyResult<(Credential, CredentialProvider)> {
        Ok((
            Credential,
            CredentialProvider(Box::new(self.0.get(opts.0)?.into_credential())),
        ))
    }
}

Credential is child class and CredentialProvider is its parent class. The rust compiler says：

282 | #[pymethods]
    | ^^^^^^^^^^^^ expected *-ptr, found struct `pyo3::PyClassInitializer`
    |
    = note: expected enum `std::result::Result<std::result::Result<*mut pyo3::ffi::PyObject, _>, _>`
               found enum `std::result::Result<std::result::Result<pyo3::PyClassInitializer<credential::Credential>, _>, _>`
    = note: this error originates in the attribute macro `pymethods` (in Nightly builds, run with -Z macro-backtrace for more info)

how to resolve it? Thanks.

[davidhewitt]

Sorry for the slow reply. I think you can achieve this by using Py::new, although it's not well documented. I'd love to make this bit of PyO3's API better.

#[pymethods]
impl CredentialProvider {
    #[args(opts = "GetOptions::default()")]
    #[pyo3(text_signature = "($self, opts)")]
    fn get(&self, opts: GetOptions) -> PyResult<Py<CredentialProvider>> {
        Py::new((
            Credential,
            CredentialProvider(Box::new(self.0.get(opts.0)?.into_credential())),
        ))
    }
}

[bachue]

@davidhewitt OK, Thanks for your reply.