How about supporting lazy loading?

[MarcWeber]

Eg cmp-buffers uses it this way:

require('cmp').register_source('bufname', require('cmp-bufname').new())

And it looks like it loads 3+ .lua files even if the registered completion is
never used.

Suggestion: Allow passing a function which returns the completion. Lazy
implementation done:

require('cmp').register_source('bufname', function() require('cmp-bufname').new(); end )

I searched for lazy and loading and I tried looking at register_source, config.set_global (referenced by cmp.setup) but didn't find anything related. So I guess the feature isn't implemented yet.