Re: [Emacs-diffs] emacs-25 f8208b6: Document the user-level features of the Xref package

[Dmitry Gutov]

On 01/21/2016 10:01 PM, Stephen Leake wrote:

> I think we should move more towards relying on "project" commands for
> operations on sets of files; xref is then mostly a tool that project
> commands use.
>
> Another way to look at this is that any xref backend should also provide
> a project backend, so the two sets of commands always operate on the
> same set of files.

I would state it like this: most projects that provide an xref backend, 
should provide a project backend as well, or at least set 
project-vc-external-roots-function. The reverse is probably also true.

The main exceptions are simplistic backends, for languages without 
strong tooling.

I thought about having xref.el depend on project.el (by, say, passing 
the current project to xref-backend-functions), but I'm less confident 
in the user-facing parts of project.el than in xref commands.

So it would make a more-stable facility depend on a less-stable one, 
unfortunately.