Automatic import management with dst

[dave]

Hey @cixel - I saw you were using dst... Thought I'd show you how to use the automatic import handling... Let me know what you think!

[cixel]

Hey, thanks for the suggestions. This is great! This is my first time dealing with AST rewriting where I couldn't just throw away unimportant comments, and I found dst from your post. It's really useful.

So, a lot of this was borrowed from other projects where I'm doing all of this with go/ast and astutil. astutil has an AddImport function which did the work for me. Initially, I just search/replaced ast --> dst. Since dstutil.AddImport doesn't exist, my instinct was just to create a drop-in replacement for what I needed myself. I had thoughts about what happens if the name newrelic is taken but decided "meh, that's a dumb name and their fault". 😛

[cixel]

FYI: I'm doing this for a meetup talk on some of the uses of AST rewriting and the transformations I wanted to focus on are injecting the init function and wrapping http.HandlerFunc (still TODO). It's unfortunate that preserving comments is by far the most involved part of the process---it kinda obscures the plot a bit.

That said, it's pretty unavoidable when talking about AST manipulation. Even if you can throw away 'lossy' comments, you still need to do a bit to re-attach comments with //go:* directives, so I don't think there's any avoiding it in my talk.

I think what I'll do is show the manipulations using ast and astutil. Then, I'll talk about the comments problem and a bit on how you're handling it with dst. Are there any key ideas you think I should present about your approach?