Racer has come on a bit since my last post. Here's a quick rundown of the main changes:

  • Method resolution got better. Racer now hunts around traits for default method implementations. This means that e.g. a completion on a Vec method gives you all the methods available, including 'is_exists()' and other methods implemented in the sub traits (see above). Racer can also resolve the type of 'self' so that it can match methods and fields when you're writing method implementations.
  • More completion information Racer now outputs some contextual info which gets included in matches - see the image above.
    (N.B. unfortunately there's a bug in my emacs bindings somewhere in the interaction with company mode which means that the extra stuff only crops up after you move the cursor. I'm not really sure why this happens, I'll try and fix it at some point.)
  • Module searching got better: Racer does a more accurate job of following 'extern crate' and nested modules. It turned out that modules didn't quite work the way I originally thought they did.
  • Racer now recognises explicit types in let expressions
    let v : Vec<uint> = ...
    This gives you a way to 'tell' Racer the type if it isn't smart enough to deduce it.
  • Internally Racer now uses iterators everywhere instead of callback functions. (I mentioned callbacks as something I didn't like about the design in a previous post).

    I originally thought iterators would solve the 'don't do the whole search if I only need the first match' problem. Unfortunately writing lazy iterators in Rust is non-trivial when the thing you're iterating is nested and recursive (like a code search). For now I've replaced the callbacks with a simpler eager solution: 'collect the results in a vector and return vec.move_iter()'.

    N.B. I did manage to cobble together a lazy iterator in one place by chaining together a bunch of procs in the central 'resolve_name' function; This has improved performance in racer - I might do the same trick for sub-trait searches.

Basically Racer is now pretty good at navigating and completing anything that does not involve lambdas, destructuring or generics. I'm planning to work on generics next.

I should say a big thanks to the people who committed patches to racer in the last couple of months, in particular rsw0x who posted a couple of fixes and has also been working on the vim plugin, Jorge Aparicio who got racer integrated with the travis build system and Micheal Gehring who dilligently kept Racer compiling in the face of breaking Rust changes.

While on the subject of contributors: I've been feeling the need for somewhere to discuss Racer recently, in particular for things that I don't have much experience with - e.g. windows support, vim + other ide plugins. I've created a google group racer-discuss; please join if you're interested in Racer.