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  • 11 min read

Inside CPython's attribute lookup

Python's attribute lookup logic seems pretty simple at a first glance: "first look in the instance __dict__, then look in its type".

However, the actual logic is much more complex because it needs to take into account the descriptor protocol, the difference between lookups on instances vs types, and what happens in presence of metaclasses.

Recently I implemented preliminary support for the descriptor protocol in SPy, which led me to investigate the CPython source code to get a better grasp on the details. This is a write up on what I found, with links to the actual C source code, to serve as a future reference.

Thanks to Hood Chatham, Siu Kwan Lam and Justin Wood for the feedback on drafts.

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  • 3 min read

Claude code modified my .bashrc without asking?

Note

This is not the classical post about running claude in YOLO mode and then complaining that it damaged the system. I have reasons to think that claude automatically modified my .bashrc to remove a line alias claude=... without asking my permission and without notifying me of the change.

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  • 4 min read

Tales with claude code: how to make it behave?

In the past weeks, I have been experimenting with using claude code to speed up development, in particular of SPy.

My experience so far reveals a clear pattern: claude excels at simple, one-shot tasks that follow existing patterns, producing commit-ready code. However, for complex tasks requiring multiple iterations, quality deteriorates significantly with each round, often necessitating complete rewrites or extensive cleanup.

Because of this, I have been looking for ways to guide it towards making it only simple steps, and to wait for my confirmation before going further. So far, I failed.

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  • 8 min read

Over the clouds: CPython, Pyodide and SPy

The Python community is awesome.

It is full of great people and minds, and interacting with people at conferences is always nice and stimulating. But one of my favorite things is that over time, after many conferences, talks, pull requests and beers, the personal relationship with some of them strengthen and they become friends.

View from a ski slope in Valtournenche, Italy

I am fortunate enough that two of them, Łukasz Langa and Hood Chatham, accepted my invitation to join me in Cervinia, at the border between Italian and Swiss Alps, for a week of hacking, winter sports and going literally over the clouds. This is a brief summary of what we did during our time together.

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  • 2 min read

hpy 0.0.2: First public release

Originally published on the HPy blog.

HPy 0.0.2 is out! This is the first version which is officially released and made available on PyPI.

The major highlight of this release is that it is supported by three different Python implementations: CPython, PyPy and GraalPython.

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HPy @ Python Language Summit

Originally published on the HPy blog.

Yesterday I had the privilege to give a talk about HPy (sildes) at the Python Language Summit 2021.

The organizers of the summit will soon publish a full report about the event (edit: now available here), but for the HPy-specific part, we got generally good feedback. Someone has a few concerns that if CPython is to change the API, HPy might not be going far enough. Others said that Python shouldn't wait for the "perfect" API if HPy can be the "good" one that helps it evolve.

Everyone was open to have HPy-compatible wheels on PyPI, once the HPy Universal ABI stays relatively stable. Many people suggested that we should really write a PEP to propose HPy as a "semi-official" API for Python.

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  • 7 min read

Hello, HPy

Originally published on the HPy blog.

HPy has been around for a while now. The initial discussion started during EuroPython 2019, in the good old times when we could still go to conferences and have real-life meetings. Since then, HPy progressed a lot from the point of view of the actual code, but we have been a bit too silent w.r.t. communicating what we are doing to the external world and to the broader Python community. Hopefully, now that this blog is online we will do a better job at periodically communicating the status of HPy, so make sure to subscribe to the RSS feed.

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  • 7 min read

HPy kick-off sprint report

Originally published on the PyPy blog.

Recently Antonio, Armin and Ronan had a small internal sprint in the beautiful city of Gdańsk to kick-off the development of HPy. Here is a brief report of what was accomplished during the sprint.

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  • 5 min read

PyPy for low-latency systems

Originally published on the PyPy blog.

PyPy for low-latency systems

Recently I have merged the gc-disable branch, introducing a couple of features which are useful when you need to respond to certain events with the lowest possible latency. This work has been kindly sponsored by Gambit Research (which, by the way, is a very cool and geeky place where to work, in case you are interested). Note also that this is a very specialized use case, so these features might not be useful for the average PyPy user, unless you have the same problems as described here.