How to add custom type conversion rule?

[evan0greenup]

For my project, if I want to add custom conversion rules between Python type and Rust type or Vice versa. Is there any official support or recommend way to do that?

[davidhewitt]

Usually implementing the FromPyObject and IntoPy<PyObject> traits will give you custom conversions.

[jnoortheen]

@davidhewitt Could you point to a complex example of implementing these traits. I am new to rust and currently wrapping the struct with #[pyclass] and duplicating the methods from the inner struct.

https://github.com/jnoortheen/xonsh-parser/blob/3f2a297e9a7bac93d9b00f317d5ca63058074f8c/xonsh_tokenizer/src/lib.rs#L14

[davidhewitt]

I'd suggest looking at the files inside PyO3's own src/conversions directory.

But it's worth noting that #[pyclass] will automatically implement for you FromPyObject for PyRef<T> as well as IntoPy<PyObject>.

[jnoortheen]

Thanks @davidhewitt , I think the src/conversions and the cargo expand of the command would suffice to export the TokInfo struct as a PyClass.