How about joining up for Python code completion? (YouCompleteMe)

[Replicating our private email discussion in a more public forum]

I’m the author of a YouCompleteMe (YCM), a recently released (Feb 2013) OSS code completion system for Vim. It’s become very popular very quickly (~1300 stars on GitHub).

YCM comes with out-of-the box support for semantic completion for C-family languages like C/C++/Objective-C/Objective-C++ (using libclang as the engine) and also has a language-agnostic identifier completer. The GIF on the project page is a thousand words and there’s also an extensive introduction there so I’ll spare you the details that you can easily grab.

Getting to the point, an external developer contributed a Jedi-based semantic completer for YCM today. YCM actually provides a generic framework for writing custom semantic completers (for any language) that can then take advantage of the code completion infrastructure that YCM provides (non-blocking operation that lets Vim continue to process events, a smart caching layer, the subsequence-based completion filtering system and the advanced completion ranking algorithm etc). You can see just how small the file for jedi-based semantic Python completion is in YCM.

I see that Jedi (which is freaking awesome btw, congrats on that) also has other features too, like goto etc. Any chance on us teaming up to bring those features to YCM? I see that you have written the jedi-vim plugin. While I haven’t tried it I’m sure it’s awesome (hey, it’s using Jedi) but I think it’s sad that we have this duplication of work. I’d also like to see YCM become a common framework for code completion in Vim, much like Syntastic is the common framework for displaying compilation/lint errors.

YCM will expand into more IDE features with go-to-definition/declaration. Basically all the useful features that one can build when one has an engine that provides a semantic understanding of the codebase. These features would be accessed through the new :YcmCompleter [completer sub-command] [sub-command arguments] interface that also recently landed. That command calls OnUserCommand on the Completer object with the arguments the user provided after the sub-command name. From then on, the Completer writer can do anything he wishes.

So my idea is to expand the functionality of YCM’s jedi_completer until it does everything jedi-vim can. That’s it. I’ll probably end up doing all this myself if no one else does but I’d love it if you could contribute pull-requests. Correct me if I’m wrong, but your goal is to build the best possible Python code completion system. You shouldn’t have to spend time on the VimScript parts and other Vim plugin boilerplate. You should be able to focus on making Jedi, the library, even better.

If you’re not interested, that’s perfectly fine. I just think it’s sad that there’s this duplication of efforts; I spent a ton of time writing the ycm_core library in C++ so that completions in Vim can be super-fast. I’d love to see others leverage that work to improve editing in Vim even more.

[josecostamartins]

To disable YCM for python i’ve put the following snippet in my .vimrc:

let g:ycm_filetype_specific_completion_to_disable = { 'python' : 1 }
let g:ycm_filetype_blacklist = { 'python' : 1 }

So far seems like everything is going as planned.

How is the conversation about a merger/integration going? You probably already thought about this, but how hard it is to make jedi-vim a module of YCM?

[davidhalter]

I think that it’s save to say that we have in some ways worked together. Jedi is used within YCM and jedi-vim has always been a side-project.

The times have been changing and language servers have emerged as the new market leader. I still think that language servers have a bit too much overhead (both in complexity and resources), but that’s probably not going to stop people from using them.

So I’m glad YCM, jedi and jedi-vim have become what they are now. Cheers to a few more years!