- SQLAlchemy by Michael Bayer: https://www.aosabook.org/en/sqlalchemy.html (nice observation of core language on top of SQL, then the separate declarative/orm system)
- LLVM by Chris Lattner: https://www.aosabook.org/en/llvm.html
- Audacity by James Crook: https://www.aosabook.org/en/audacity.html (interesting mentionings of wxwigets)
Note that pretty much everything in volume 1 and 2 is interesting, though!
What would be nice to see, non-exhaustive:
- Blender: Especially 2.80, an analysis of its GUI/widgets, integrated python scripting, and everything else (wiring into graphics cards, rendering, shapes). There's a lot of stuff that could be covered
- Gimp / Inkscape / Krita
- Saltstack / Ansible / Fabric or PyInvoke : These have nice abstractions on top of system functionality / programs and delivery magic that'd be fun to go into
- GTK, QT
- Tiling window managers, e.g. i3, swaywm, awesome
- Wayland, Xorg
- Kdevelop, VSCode, Atom, Electron
- React, Vue, Angular (it'd be nce to see more js)
- Android SDK
- Unity3D SDK, Unreal SDK
- .NET Core
- black (python formatter), clang-format, prettier
- docutils, sphinx, pandoc
- systemd, mesa, cairo, pulseaudio
- implementations of python (cpython), typescript, lua, luajit, haskell ghc, swift