[LexiMax]

The Python 3 upgrade process for many projects was incredibly painful. "Mercurial’s journey to and reflections on Python 3" should be required reading for anybody with rose-tinted glasses of the migration.

https://gregoryszorc.com/blog/2020/01/13/mercurial%27s-journ...

There was, of course, a Hacker News thread discussing the article, and a fair few people decided to blame the Mercurial developers for handling the migration inelegantly. Because that's how you win over an audience of developers - reassuring them that if Python has a backwards-compatibility break, Python fans will go out of your way to try and blame you for writing bad code. And not, perhaps, the fact that Python was missing things like a u string prefix and % bytestring formatting until 3.3 (2012) and 3.5 (2015!!!) respectively.

If I sound peeved, I really loved Python in the 2.x days, and the way the 3.x transition was handled broke my heart and prevented me from using the language for pretty much an entire decade. There are lessons to be learned from the transition, but not if we ignore the real problems that the transition caused. More importantly, we need to recognize that Python is not the Python we know today because of how "well" the transition was handled, but because Numpy and Matplotlib swooped in and gave Python new niches to excel in at just the right time.