Скачать или смотреть Understanding Pybind C+ + for Multiple Python Versions: Do You Really Need to Compile Separately?

Discover why compiling C+ + extensions for each Python version is essential when working with `pybind`. Learn about version compatibility and best practices for creating Python wheels.
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Understanding Pybind C+ + for Multiple Python Versions: Do You Really Need to Compile Separately?

When developing Python extensions using C+ + , especially with tools like pybind11, managing compatibility across different Python versions can be quite challenging. Transitioning from older versions of Python to newer ones often poses questions about module compatibility and the compilation process. A common query arises: Is it necessary to compile a .pyd module separately for each Python version?

The Challenge of Version Compatibility

As many developers have experienced, switching from an older version of Python, such as Python 3.7, to a more modern release can create hurdles in maintaining existing code and modules. You may find yourself needing to support both versions for a period of time, particularly when transitioning to new environments. This is where understanding the implications of compiling C+ + code introduces complexity.

The Importance of Separate Compilation

After gathering information from resources and documentation, you may wonder about just packaging the .pyd file generated for one version of Python into wheels designated for another. However, the reality is quite different due to several reasons:

1. ABI Compatibility

The Application Binary Interface (ABI) of CPython varies between Python versions. This means that even minor changes in Python can lead to potentially incompatible .pyd files.

For instance, the ABI might dictate differences in data structuring, function calling conventions, or error handling between Python releases.

2. Reasons for Compiling Separately

Stable Functionality: Each version may utilize improved functions or libraries that afford newer features or bug fixes.

Error Prevention: Compiling a module targeting a specific Python version allows for accurate testing and error handling tailored to that environment, ensuring robustness.

Future-Proofing: As Python continues to evolve, being diligent about compiling each .pyd file means your module remains functional across the board.

The Process of Supporting Multiple Versions

When planning to support multiple Python versions using pybind, a recommended approach would be:

Two Separate Build Processes:

Build for Python 3.7: Ensure your existing code runs flawlessly on the old version.

Build for the Newer Version: While addressing any compatibility issues that arise in the context of the latest version.

Steps to Build Using CMake and pybind11

Setup Environment:

Make sure to have pybind11 and CMake installed for both Python versions.

CMake Configuration:

Create a CMake configuration that specifies the target Python version.

Use conditionals or profiles to specify builds depending on the Python version.

Compilation:

Execute the cmake and make commands individually for both versions. For example:

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Repeat the above commands for your newer Python version.

Testing:

After compilation, test the generated .pyd files with the respective versions to ensure everything works as expected.

Packaging into Wheels:

Finally, package the compiled modules into wheel files to distribute.

Conclusion

In conclusion, it is indeed crucial to compile your C+ + extensions separately for each targeted Python version, despite the inclination to circumvent the second compilation step. The nuances of compatibility, as evidenced by changes in the CPython ABI, underline the necessity for targeted builds. By adhering to this best practice, you can ensure a robust, well-functioning module across Python versions while maintaining quality as you transition from older to newer environments.

With the right setup, your exper