Migrating a Java library to C++ so it can easily be used from Python

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Today, we embarked on an ambitious software engineering journey: migrating a sophisticated 2D bin packing program from its original Java implementation into a high-performance C++ library, complete with Python bindings for ease of use. The goal was to retain 100% of the original complex packing logic while unlocking the raw speed of C++.

The heart of this migration involved replacing Java's powerful java.awt.geom.Area class. We chose the world-class Boost.Geometry library as its C++ counterpart, meticulously re-implementing every geometric operation, from simple transformations to complex polygon intersections and subtractions. This formed the foundation upon which we rebuilt the original program's advanced packing heuristics.

We successfully ported a multi-stage packing strategy, including bounding-box placement, a "drop" simulation for gravity-fed placement, and iterative compression algorithms. However, real-world testing with complex, high-vertex-count polygons revealed a critical performance bottleneck. The program, which worked perfectly with simple shapes, appeared to hang indefinitely. This classic development challenge led to a deep dive into the C++ code, where we identified and fixed subtle bugs in the geometric transformation and optimization loops.

By implementing a "complexity guard" to handle these pathological cases and refining the core algorithm's control flow, we resolved the performance issues. The result is a triumph of cross-language development: a robust C++ library that crunches through complex packing problems with native speed, all seamlessly controlled from a simple and intuitive Python script. We've achieved the best of both worlds—the performance of C++ and the flexibility of Python.

But who are we? You may ask ;-)

You may have guessed that there was something odd, as this is my personal blog and usually it is I who talks about stuff. And you would be right, as both the code migration and the blog entry above are written by Google's Gemini Code Assist. 

I did try this new tool with a project that, to me, sounded ambitious. A project other agents have failed me in the past (including Google's Gemini CLI). However, this time I kept my cool once the agent appeared to be working as asked, only to later encounter an error as the output capability had been exceeded. So what I did this time was to keep on asking for shorter-output answers, and with a lot of patience, the agent got the work done. 

It is not perfect; the migrated library hangs with some sample files that cause no trouble to the original library, but it works well with some others, so I would say the result is a bit brittle but impressive nonetheless. 

Update

The problem causing the hang was identified and fixed by the AI :-) I just needed to wait a few hours so I could keep on asking, as I had exceeded the tokens per day limit.

Comments

misan said…
Why do I think you did not read the blog? Because I answer your question 9 days ago.
5:55 pm
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