Functions implemented with macro are not treated as python methods in block #[pymethod]

[n0b0dyCN]

Bug Description

Example code:

use pyo3::prelude::*;

#[pyclass]
pub struct A;

macro_rules! impl_method {
    ($fn:ident) => {
        pub fn $fn(&self) -> PyResult<()> {
            println!("{}", stringify!($fn));
            Ok(())
        }
    };
}

#[pymethods]
impl A {
    pub fn a(&self) -> PyResult<()> {
        println!("a");
        Ok(())
    }

    impl_method!(b);
    impl_method!(c);
}

#[pymodule]
fn pyo3_example(_py: Python<'_>, m: &PyModule) -> PyResult<()> {
    m.add_class::<A>()?;
    Ok(())
}

Test python code:

from pyo3_example import A

print(dir(A))

Expect behaviour: function a, b and c should be printed.

Current behavious: only function a is printed.

Steps to Reproduce

For quick reproduce, clone repo https://github.com/n0b0dyCN/pyo3_example and follow readme.

Backtrace

No response

Your operating system and version

Linux MY_HOST_NAME 5.15.0-56-generic #62~20.04.1-Ubuntu SMP Tue Nov 22 21:24:20 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

Your Python version (python --version)

Python 3.8.10

Your Rust version (rustc --version)

rustc 1.65.0-nightly (d394408fb 2022-08-07)

Your PyO3 version

0.17.3

How did you install python? Did you use a virtualenv?

use python -m venv

Additional Info

No response

[davidhewitt]

This is known and a fundamental limitation of how Rust macros work. The pymethods macro just sees the unexpanded impl_method! syntax. Instead you should create a bigger impl_methods! macro which expands to a #[pymethods].

We can improve the documentation and error for this case.

[n0b0dyCN]

This is known and a fundamental limitation of how Rust macros work. The pymethods macro just sees the unexpanded impl_method! syntax. Instead you should create a bigger impl_methods! macro which expands to a #[pymethods].

We can improve the documentation and error for this case.

Thanks for your reply.