bug#68958: [PATCH] Support bookmarking Xref results buffers

[Eshel Yaron via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Hi,

Dmitry Gutov <dmitry@gutov.dev> writes:

> On 07/02/2024 14:25, Eli Zaretskii wrote:
>>> To make this happen, we need to propagate some more information to the
>>> "*xref*" buffer (and any other Xref fronted).  We do this, without
>>> breaking compatibility, by setting a new variable from inside the xrefs
>>> fetcher function.  The frontend can examine this variable to learn all
>>> about the source of the fetched xrefs after invoking the fetcher.
>>> Namely, the "*xref*" buffer uses this information to create bookmarks.
>> Thanks.  Frankly, I'm surprised we need such a complex changeset for
>> supporting such a simple extension, but I'll let Dmitry judge that.
>
> A lot of changes seem to stem from the desire to add detailed info
> into the bookmarks's name (including the identifier being searched,
> the search type, and the xref backend in use).

That's not the case.  The changes are all meant to facilitate creating
bookmarks that you can restore at a later session.  AFAICT the backend,
identifier and search type (kind) are a required for that, no?  We use
them to suggest a meaningful bookmark name, but that's just a bonus.

> At the moment our code doesn't save all of those separately, just
> combines them in xref--fetcher.
>
> So whether the patch has to be complex would depend on whether we
> really need to have bookmark names look exactly like proposed. Though
> I'd rewrite it a little even in that case.

Again, the name of the bookmark is really not the focus here.  We can't
persist the value of xref--fetcher, since it's an anonymous function, so
we get all the info needed to /recreate/ that function to the frontend.
If there's another (simpler?) way to provide this feature, please do tell.


Best,

Eshel