One of the stand-out collaborations of my career has been with my buddy Damien George. He's the creator of MicroPython ~ a lean and efficient implementation of the Python programming language optimised to run in constrained environments. When Damien created MicroPython I think he imagined "constrained environments" to mean microcontrollers - the small single chip computers beloved of embedded systems engineers, Internet of Things enthusiasts and the Maker community.
Little did he realise that MicroPython was an amazing fit for another computing context: the browser.
The browser is an interesting space in which to work because of its unique combinations of constraints.
Firstly, everything needed to view a web page needs to be delivered over the network. So, the smaller the asset to be delivered can be, the better. MicroPython, when compressed for delivery to the browser is only around 170k in size - smaller than most images you find on most websites.
Secondly, the browser is perhaps the world's most battle tested sand boxed computing environment. By this I mean that web browsers encounter all sorts of interesting, nefarious, ill-performing, badly written and otherwise shonky code. Such code should be constrained into a virtual sandbox, so it can't do any damage to the user's wider system. Because of the recent development of web assembly (shortened to WASM ~ a sort of virtual microprocessor working in the browser), code written in C can be compiled to run in the browser. MicroPython is written in C and Damien and his collaborators have worked together to create a port for web assembly.
Third and finally, the browser makes available to the developer of websites a
globalThis, through which all the other objects,
functions and data structures needed to
access the capabilities of the browser
are made available. By constraining developers to a single means of interacting
with the browser, there is only one way to go about making things happen.
MicroPython compiled to WASM has access to the full capabilities of the
sandboxed browser thanks to some of Damien's recent work on a foreign function
Given this context, what does MicroPython allow you to do?
From within MicroPython running in the browser, one simply imports the
globalThis in the browser. It makes interacting with the browser
from MicroPython an absolute joy. It's worth pointing out that Damien's work is
based upon the
js work done as part of the
Pyodide project (a version of the CPython
interpreter for the browser), so no matter the version of Python you use in the
browser, you access the browser's capabilities in exactly the same way.
But recently, there was a problem.
This wasn't a good situation to find oneself in, a few days before presenting at one of the Python world's largest and most prestigious conferences.
Damien and I decided to debug the problem, and we recorded ourselves doing so because Andrea wasn't available at the time of our call. We figured that if he could watch our debugging session, he might spot something we hadn't and suggest a fix.
In any case, what followed was a lot of fun, and the video of the debugging session is embedded below.
There are some things you need to know before you watch the video:
- Damien is an expert in C (the language used to implement MicroPython) and clearly knows his way around the MicroPython codebase including the FFI that kept crashing. I am familiar enough with C to be able to read it, but not very experienced at writing it, and I certainly don't know anything about the MicroPython internals, including the FFI.
- We were using a collaboration technique called pair programming: where one developer (Damien) is the "pilot" with the other developer (me) acting as "co-pilot". As you'll see in the video, Damien was sharing his screen so I could see what he was looking at and he'd often describe things, processes or problems to me, only for me to confirm them, explain them back or ask questions as a way to help maintain focus. As the one most ignorant of the language and code-base, I was in a good position to play the beginner to Damien's expert, and ask for clarifications.
- Our debugging involved taking very careful steps to investigate and change the code so the problem was (happily) eventually revealed, tested and fixed. As the Chinese proverb explains: when crossing a river, it's best to do so slowly and by feeling with one's toes.
- Both of us were having a lot of fun in different ways. Damien was clearly fascinated by delving into the problem. I was enjoying Damien's virtuosic debugging performance, and found out some fun stuff as we went along.
So grab your popcorn, and enjoy the show: