Re: master 7fc0292: Allow completion styles to adjust completion metadata

[João Távora]

You're right, this version didn't work for many reasons. Once we get cl-defgeneric to work, we can fix it to work by return value, as you suggest...

João

On Sat, Oct 26, 2019, 17:12 Stefan Monnier <address@hidden> wrote:

> +(cl-defgeneric completion-adjust-metadata-for-style (style metadata)
> +  "Adjust METADATA of current completion according to STYLE."
> +  (:method (_style _metadata) nil) ; nop by default

Hmm... if "nop" is to return nil, it means it works by side-effect, but
if the metadata is `nil` to start with, there's no side-effect that can
turn it into a non-nil value, right?

So I think it should work by returning a new metadata and hence "nop"
should be to return `metadata` unmodified.

> +     (let ((alist (cdr metadata)))
> +       (setf (alist-get 'display-sort-function alist)
> +             (compose-flex-sort-fn (alist-get 'display-sort-function alist)))
> +       (setf (alist-get 'cycle-sort-function alist)
> +             (compose-flex-sort-fn (alist-get 'cycle-sort-function alist)))

This works by side-effecting the alist, but those entries may (and
usually) come from immediate constants in the code, so this is
like "self-modifying code" :-(

> +       metadata))))

I see here you do return the metadata, good.

> +        (result-and-style
> +         (completion--some
> +          (lambda (style)
> +            (let ((probe (funcall (nth n (assq style
> +                                               completion-styles-alist))
> +                                  string table pred point)))
> +              (and probe (cons probe style))))
> +          (completion--styles metadata))))
> +    (completion-adjust-metadata-for-style (cdr result-and-style) metadata)
>      (if requote

But here it appears you're not using the return value, unless I'm
missing something.


        Stefan