bug#44611: Prefix arg for xref-goto-xref

[Dmitry Gutov]

On 27.12.2020 20:21, Eli Zaretskii wrote:
> > > This works both ways: if you want TAB to do something other than its
> > > default, you can rebind it for you, right?
> > This is not about my personal preferences.
> Your original explanation of the rationale was that you always press
> TAB because you are used to it in Grep buffers.

Avoiding unnecessary ad-hoc differences is not just about any personal 
preference.

> > > That contradicts what Dmitry said: that the current Xref UI moves away
> > > of the completion UI, and towards compilation-mode and grep-mode.
> > > There, deleting the window with C-j will look odd, I think.
> > There are two modes: xref-show-xrefs and xref-show-defs.
> > xref-show-xrefs is similar to grep, whereas xref-show-defs
> > resembles the Completion UI where C-j makes sense.
> AFAIU, Dmitry didn't like the proposal to have different bindings in
> these two modes.

Two buffers that look exactly the same shouldn't behave differently. I 
think it's just basic usability.

What we could do instead, is change the default value of 
xref-show-xrefs-function to use some new function that would use a new 
major mode with the (slightly) new bindings which you have discussed 
with Juri.

And *also* change the default value of xref-show-definitions-function to 
one of the alternative functions, which already behave in some notably 
different way than xref--show-xref-buffer.

I'm not sure what we would buy with such a combination, however, given 
that it will create an bigger difference in behavior than simply 
changing a key binding (*). But the latter change in the default seems 
to be a Good Thing either way. Maybe we should put it to a vote.

(*) I guess you might like that the user could customize 
xref-show-definitions-function back to a value where TAB behaves like it 
did in Emacs 27? Although they could change the key binding back just as 
well with a couple of line of Emacs Lisp, one can't do that via Customize.