Ask HN: What are the “best” codebases that you've encountered?

Second this; Postgres codebase is what got me out of the "good code is self documenting" nonsense. For those of us in the database space it is an incredible resource - and overall a great example of good code.

sqlite is much less complex, but similarly approachable.

In more recent examples, I think you see a lot of this same reader-centric pragmatic ethos in many Go projects. The Kubernetes codebase comes to mind as a very large tome that remains approachable. And the Go stdlib, of course.

Java generally falls on the opposite side, but there are counterexamples. A lot of Martin Thompsons code eschews Java "best practices" in favor of good code. Seeing competent people in the Java space "break the rules" helps.. though of course Java is forever hampered by having internalized illegible patterns as best practices in the first place.

It's a shame because at least the OpenJDK implementation of the standard library in Java is generally quite good, especially around the concurrency parts. Clean, easy to follow, reasonable comments. But of course that's Java written by C developers, mostly.

I love Qt, and Qt has a great cross platform API. However Qt uses a lot of Qt-Only idioms, in particular there is has simplified memory management based on parent/child relationships (all children are deleted with parents), and also "COW" copy on write containers that can simplify programming but make it harder to reason about memory allocation.

Further, all internal classes also include a PIMPL (d-pointer or data pointer) to hide internal details from API customers.

IMO, The d-pointer makes stuff much more difficult to read, and the Qt idioms are probably only useful if you are a Qt developer. So maybe might not be useful for you if you are on a non-Qt project.

Java: joda-time

C: redis

Python: scikit-learn

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Edit: formatting

For canonical C code, without a doubt I would say Redis and Postgres. Redis is written and annotated in a way that even someone with a cursory knowledge of C can understand what's going on.

For Python, I really like how SQLAlchemy is written and designed.

For Rust, ripgrep stands out as a sterling example of how to write a powerful low-level utility like that.

Anything by burntsushi, but especially xsv and ripgrep:

xsv: https://github.com/BurntSushi/xsv

ripgrep: https://github.com/BurntSushi/ripgrep

His code typically has extensive tests, helpful comments, and logical structure. It was fun trying to imitate his style when writing a PR for xsv.

The Quake 2 engine was also pretty interesting: It was almost totally undocumented, and it had plenty of weird things going on. But I could count on the weird things being there for a reason, if only I thought about it long enough.