Ask HN: What source code is worth studying?

Do you generate tags and hop around functions as you discover them? Do you do a high level overview of the important bits first, and then dive in later? I am sure it is different for everyone, but would still be interested to read about others approaches.

I've had this idea for awhile about bringing up a project in a methodical way in its source control history, and adding new features in a similar manner, so that it would be easier to introduce a codebase to those starting out in it. The problem with lots of large codebases is that as time goes on, configuration details or special cases are added on that obscure the meat of the program. If it were trivial to see the early version, and its evolution, it would be easy to pick out the mental model of what the code actually does.

C++: (Complex software with elegance + performance )

  Dart source code

  V8 source code (Same people as Dart)

  LevelDB

  Chrome (the only downside: too much virtual dispatch ->   "javism")

  SQLite

  Redis

  Nginx

  Solaris and Freebsd

  Rich Hickey implementation of the clojure runtime in Java 
 (it was there in 2009.. maybe now this is in clojure itself??)

  The Go standard libraries

But one quickly realizes that the concept of software license restrictions is a fundamental reason for the strength and momentum of open source software. Therefore, it must be true that a central tenant of being a good developer is to respect software licenses. Not merely respect them to the letter of how they're written, but to respect their spirit as well. If an author wishes you don't do something with their code, then you don't do it. There are plenty of reasons why this should be the case, but the most compelling for me is that it'd be lame to ignore the author's wishes while using their work, even if the author won't ever know about it.

If people are still feeling tempted to lift code, well... Remember that you only get to destroy your reputation once.