I've spent a lot of time using Docker recently and I've been pleasantly surprised. Once you grok the concepts, the tooling is slick.
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I've started keeping a list of particularly interesting bugs and patches that I've worked on: https://github.com/Wilfred/interesting-code
The time that I once removed *a single closing paren* in Emacs is still my favourite.
I made some changes to a node express project that I haven't touched in almost five years. I was pleasantly surprised that I only needed to update one dependency to get it working again!
(It was sqlite3, which is a native dependency using node-gyp.)
I've been building an 'extract function' refactor feature. It's surprisingly nuanced.
Where do you put the extracted function? Once you've done the static analysis, what order do you use for the parameters?