easybind

Simple self-registering helpers for distributed nanobind bindings.

Install

pip install pymergetic-easybind

Platforms: PyPI ships manylinux (glibc 2.28+) and Windows amd64 wheels for CPython 3.11–3.14. macOS is not built in CI yet. On unsupported platforms pip may fall back to the sdist and require a local C++ toolchain.

import pymergetic.easybind
from pymergetic.easybind import sample  # optional demo module

PyPI project: pymergetic-easybind (install name). Import: pymergetic.easybind.

Version: Set by Git tags at build time (v0.1.0, …) via setuptools-scm; see RELEASING.md. At runtime, pymergetic.easybind._version.__version__ is written when the wheel is built (or use importlib.metadata.version("pymergetic-easybind")).

Local dev / clangd

An editable install configures CMake under ./build/ and generates build/compile_commands.json, which clangd picks up via .clangd — same database as the Python build, no second configure step:

uv pip install -e .    # or: pip install -e .

If you need compile_commands.json without pip, run scripts/clangd-update.sh (plain cmake -S . -B build …).

Python layer

The Python package is implemented as native extensions. It exposes:

• pymergetic.easybind (core helpers and macros)
• pymergetic.easybind.module (module tree API)
• pymergetic.easybind.sample (demo bindings)

Build-time SDK

Installed wheels ship CMake helpers under pymergetic/easybind/cmake/:

• easybind_pip.cmake — easybind_pip_setup() finds Python, nanobind (pip), libeasybind, and include roots for #include <pymergetic/easybind/...>, then pulls in easybind_dependencies.cmake. Helpers: easybind_pip_link_magic_enum(target), easybind_pip_set_rpath_next_to_easybind(target easybind_pkg_dir).
• easybind_dependencies.cmake — pins nanobind, magic_enum, reflect-cpp (same tags as this repo). Use easybind_fetch_third_party_deps() to pull all three, or easybind_fetch_nanobind() / easybind_fetch_magic_enum() / easybind_fetch_reflect_cpp() when you only need a subset (e.g. pip already provides nanobind, so call only easybind_fetch_magic_enum()).

Typical consumer bootstrap:

find_package(Python REQUIRED COMPONENTS Interpreter Development.Module)
execute_process(COMMAND "${Python_EXECUTABLE}" -c
  "import pathlib, pymergetic.easybind; print(pathlib.Path(pymergetic.easybind.__file__).resolve().parent / 'cmake' / 'easybind_pip.cmake')"
  OUTPUT_VARIABLE _eb_pip OUTPUT_STRIP_TRAILING_WHITESPACE COMMAND_ERROR_IS_FATAL ANY)
include("${_eb_pip}")
easybind_pip_setup()
easybind_fetch_magic_enum()   # if you include easybind headers that need magic_enum

When developing inside this repository, easybind_add_extension(...) is defined in the top-level CMakeLists.txt (not shipped in the wheel).

Devtools (release / pin bumps)

Implemented in pymergetic.common.devtools (pymergetic-common). Install via pymergetic-easybind (depends on common) or uv sync.

pymergetic-pin-pyproject --project-root packages/easybind --dry-run
pymergetic-release-tag --project-root packages/easybind --dry-run
pymergetic-wait-pypi --project-root packages/easybind

See pymergetic-common RELEASING.md and from pymergetic.common.devtools import ….

Core idea

• Each namespace/module defines a ModuleNode and a bind callback.
• The module entry point calls apply_init to run the callback and recurse.
• Submodules are created on demand and registered in sys.modules.
• Shared-object modules are marked so recursion stops at their boundary.
• A minimal sample module lives at pymergetic.easybind.sample.

Developer note: layout rules

• __init__.cpp marks the Python boundary (NB_MODULE) for a package/module.
• node.cpp/.hpp is the pure C++ module-tree core.
• ns_module.hpp defines the EASYBIND_NS_MODULE* macros.
• Directory layout mirrors namespaces and Python modules.

Smallest possible example

1) Define a C++ type (normal code)

#pragma once

#include <string>

struct PeerInfo {
    std::string peer_id;
    int transport = 0;
};

2) Bind it in a separate file (module node)

#include <pymergetic/easybind/bind.hpp>

struct PeerInfo;  // forward declare or include the header

EASYBIND_NS_MODULE(my_pkg, m, false, {
    nanobind::class_<PeerInfo>(m, "PeerInfo")
        .def(nanobind::init<>())
        .def_rw("peer_id", &PeerInfo::peer_id)
        .def_rw("transport", &PeerInfo::transport);
});

3) Module entry point (shared-object boundary)

Use this only for the package that has its own .so and NB_MODULE entry point. Do not pair it with EASYBIND_NS_MODULE for the same my_pkg name. If you need to add bindings from another file, use EASYBIND_NS_MODULE_EXTEND to extend the same module node instead.

#include <pymergetic/easybind/bind.hpp>

EASYBIND_NS_MODULE_SHARED_OBJECT(my_pkg, my_pkg, m, true, {
    m.doc() = "my_pkg module";
});

4) Extend from another file

#include <pymergetic/easybind/bind.hpp>

EASYBIND_NS_MODULE_EXTEND(my_pkg, m, {
    m.def("ping", [] { return "pong"; });
});