Doxystub

What is it ?

This package generates stubs (.pyi file) for a python module created with Boost Python, leveraging doxygen documentation.

Setting up

Requirement

doxystub needs to know the mapping between C++ and Python classes. To that end, you should wrap your calls to class_ as follow:

// doxystub.h
#pragma once

#include <boost/python.hpp>

/**
 * This wrapper adds a __cxx_class__ method on the exposed class, allowing to retrieve the original
 * C++ type of the object from Python.
 */
template <class W, class X1 = boost::python::detail::not_specified, class X2 = boost::python::detail::not_specified,
          class X3 = boost::python::detail::not_specified, typename... Args>
boost::python::class_<W, X1, X2, X3> class__(Args... args)
{
  return boost::python::class_<W, X1, X2>(args...).def(
      "__cxx_class__", +[]() { return boost::core::demangle(typeid(W).name()); });
}

Simply keep the above snippet in a header file, and use class__ instead of class_ to expose your classes. This will provide the __cxx_class__ method, used by doxystub to retrieve the mapping with C++ types.

Usage

You can install doxystub using pip:

pip install doxystub

And then use it as follows:

doxystub -m my_module -d path/to/doxygen -o my_module.pyi

In CMakeLists.txt

The following snippet can be used to trigger stubs generation at the end of your build

add_custom_command(
    TARGET my_module POST_BUILD
    COMMAND doxystub
        --module my_module
        --doxygen_directory "${CMAKE_CURRENT_SOURCE_DIR}"
        --output "${CMAKE_BINARY_DIR}/${PYTHON_SITELIB}/my_module.pyi"
    WORKING_DIRECTORY "${CMAKE_BINARY_DIR}/${PYTHON_SITELIB}"
    COMMENT "Generating stubs..."
)

Behaviour and remarks

General process

doxystub will try, for each method, to find a method with corresponding name from doxygen parsing.

Custom methods and variables

If you define custom methods and variables, that doesn't exist in doxygen, you can specify the arguments types and the docstring manually. doxystub will parse the Boost.Python docstring to try to extract information:

class_<Something>("Something", init<>())
    .def("my_method", +[](Something &s, int j) { return 42; }, args("self", "j"), "A custom method")
    .add_property("my_property", +[]() { return 123; }, "My property [int]")
    ;

Note that type of non-doxygen properties is unknown. It can be overridden using [type] at the end of your description.