Widget completion and completion front ends

[Lennart Borgman]

I just looked a bit at company-mode which is a completion front end
for at point context completions (like intellisense etc). Since I
found it great I wondered if it would be possible to get widget
completions to work with it.

It is not possible (AFAICS). The reason is the structure specifying
completion functions for widgets. They specify a function for doing
completions, not a function for getting completion candidates. For
using different completion front ends specifying a function to get
completion candidates is necessary.

Specifying a function for completion candidates in `define-widget'
would also make it possible to get rid of the need to specify some
other functions (like :prompt-match, :match-alternatives and
:validate) for simple cases.

Wouldn't it be good to do this and depreciate :complete-function (at
least as default) and instead add something like
:completion-candidates? Giving :completion-candidates a suitable
argument list it could be used also for the other functions above.