Comment by almostgotcaught

> I really think a big switch() (or anything that works but is simpler) would be a lot easier to understand.

It's much easier conceptually to implement this using recursion instead of a while loop and a token stack (it's basically DFS). So I disagree with you there.

> The other reason I dislike this kind of stuffs is that I have someone in the team who really likes to use patterns for every piece of code. It's kinda difficult to tell whether it is over-engineering or not, but my principle is that intuition always beats less lines of code (or DRY), unless it is absurdly more lines of code or repetition. And to test that principle you just grab a newbie and see which one makes more sense to him

I'm with you - I really don't give a shit about patterns (which was my whole original point - who cares). But that last part I don't agree with - systems code (like a parser) doesn't need to be legible to a noob. Of course we're talking about a textbook so your probably right but like I said most production parsers and AST traversals are written exactly this same way. So anyone learning this stuff hoping to get a job doing it should just get used to it.