docs: added pyo3-nest to the tools

[ppmpreetham]

Added pyo3-nest to the tools.

Example

use pyo3::prelude::*;
use pyo3_nest::{submodule, add_classes, add_functions};

#[pyclass]
struct Router;

#[pyclass]
struct Route;

#[pyfunction]
fn hello() -> &'static str {
    "Hello from Rust!"
}

#[pymodule]
fn my_extension(m: &Bound<'_, PyModule>) -> PyResult<()> {
    // top level classes
    add_classes!(m, Router);

    // nested submodules
    submodule!(m, "routing", add_classes!(Router, Route));
    submodule!(m, "utils", add_functions!(hello));

    // classes + functions
    submodule!(m, "api.v1.responses", 
        add_classes!(JSONResponse, ErrorResponse) && 
        add_functions!(success_response, error_response)
    );

    Ok(())
}

In Python:

from my_extension import Router
from my_extension.routing import Route
from my_extension.api.v1.responses import JSONResponse, success_response

Before

let routing = PyModule::new(py, "routing")?;
routing.add_class::<Router>()?;
routing.add_class::<Route>()?;
m.add_submodule(&routing)?;

After

submodule!(m, "routing", add_classes!(Router, Route));

[codspeed-hq]

Merging this PR will degrade performance by 23.26%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

❌ 1 regressed benchmark
✅ 139 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
❌	into_u128_max	1.5 µs	2 µs	-23.26%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing ppmpreetham:patch-1 (662d623) with main (022f8ce)}

[davidhewitt]

Thanks for the PR.

I think this looks like a reimplementation of what we're calling "declarative modules", i.e. #[pymodule] applied to mod items rather than to fn items.

See e.g. the first example in https://pyo3.rs/v0.29.0/module.html#python-modules

This is important because we use the declarative form to make the experimental-inspect feature work; I imagine we will one day deprecate the function form.

With this in mind, I'm afraid I don't think it's a good idea to recommend this project to PyO3 users. I hope you understand, please do feel welcome to convince me otherwise!