Create Hybrid C++/Python modules in tudatpy¶
This example shows how to create a hybrid C++/Python module in tudatpy.
Note
If you’re not familiar with the Python import system, it may be useful for you to check out the developer documentation on kernel module exposure and autocompletion in tudatpy first.
The goal of this guide is to briefly explain how to create a hybrid C++/Python module in tudatpy. This is useful to combine C++ and Python functionality in a single tudatpy module.
We will first consider the case in which you have implemented a new class, function or other object in a C++ tudat kernel module, a Python module which uses this object to provide some functionality, and want to expose them both.
Then, we will consider the case in which you have created an entirely new C++ tudat kernel module, a Python script which makes use of its members to provide some functionality, and want to expose them both.
Combining C++ and Python functionality in an existing tudatpy module¶
The directory tudatpy/tudatpy contains all tudatpy modules, both the ones which wrap C++ tudat kernel modules and those which are pure Python.
Find the tudatpy module which wraps the C++ tudat kernel module you want to combine with your Python module.
Place your Python module inside the tudatpy module wrapping the C++ tudat kernel module. This will allow you to import the Python module and use its members, as well as the members of the kernel module.
Compile tudatpy using build_and_expose_kernel.sh. This will expose the C++ tudat kernel module by wrapping it in a Python module (as well as provide Python autocompletions for all its members).
You’re done! You have now combined Python and C++ inside a single tudatpy module.
To get a feeling of how the final result should look like, you can check out the tudatpy.trajectory_design tudatpy module, which combines the C++ shape_based_thrust and transfer_trajectory modules and the Python porkchop module.
Note
You can make use of the __init__.py of the tudatpy module which wraps the C++ tudat kernel module to ease the import of the Python functionality you’ve just added to it.
For example, you could add the following lines to the __init__.py of the tudatpy.trajectory_design module to make it easier to import the trajectory_design.porkchop.porkchop function:
from tudatpy.trajectory_design.porkchop import porkchop
Combining C++ and Python functionality in a new tudatpy module¶
Two components are needed for this:
A C++ tudat kernel module, exposed to Python using pybind11
A Python wrapper of the module, which exposes it through tudatpy
Create a C++ tudat module and expose to Python using pybind11¶
Please refer to the developer docs on exposing C++ modules for a detailed explanation.
Expose the C++ tudat kernel module through tudatpy¶
Once you have created your C++ kernel module, compile tudatpy using build_and_expose_kernel.sh. This will expose the new C++ tudat kernel module by wrapping it in a Python module (as well as provide Python autocompletions for all its members).
Place your Python module inside the tudatpy module wrapping the C++ tudat kernel module¶
Move the Python module you want to combine with the kernel module inside the Python module which wraps the kernel module. This will allow you to import the Python module and use its members, as well as the members of the kernel module.
To get a feeling of how the final result should look like, you can check out the tudatpy.trajectory_design tudatpy module, which combines the C++ shape_based_thrust and transfer_trajectory modules and the Python porkchop module.
Note
You can make use of the __init__.py of the tudatpy module which wraps the C++ tudat kernel module to ease the import of the Python functionality you’ve just added to it.
For example, you could add the following lines to the __init__.py of the tudatpy.trajectory_design module to make it easier to import the trajectory_design.porkchop.porkchop function:
from tudatpy.trajectory_design.porkchop import porkchop