Re: [Emacs-diffs] emacs-26 b1aaa72: Improve documentation of Xref

[Dmitry Gutov <dgutov@yandex.ru>]

On 3/12/18 6:04 PM, Eli Zaretskii wrote:

> This is not about fairness at all, and I'm surprised, to say the
> least, that you judge the text in these terms.

Just talking about what impression the wording might leave. Your new 
update is better, thank you.

> This is about describing a command whose only raison d'être is to
> provide a "fire escape" when the default method invoked by M-. fails
> to find identifiers, because for some reason they are "out of scope"
> for that default method.

I didn't mean to ascribe any ill intent to the author.

>> More importantly, I think the Reddit user's problem (which has probably resulted in this manual update) was that they thought, for some reason, that xref-find-definitions will always use the tags table. And that them visiting it should affect what xref-find-definitions finds.
> 
> No, I wrote that because it took me some time to find this command,
> although I vaguely remembered something like that should be possible.

Still, there is that scenario from Reddit:

"M-. (bound to xref-find-definitions) can't find any definitions. I 
visit-tags-file, set tags-file-name and tags-table-list manaully, 
generated the file with etags and ctags, everything. No luck"

Basically, there was no reason to expect navigation to those symbols to 
work, except that the user had created and visited a tags table 
containing them. So I think the surprise really was that M-. didn't use 
the current tags table.

>> So if there's some place in the manual that leaves them with that impression, I think it should be updated.
> 
> Feel free to point out such place(s) if you find them.

Upon re-reading, I think the manual is indeed pretty clear. And we can 
ascribe the problem mostly to old habits.

> Irrelevant.  Once again, this command is only for when M-. fails to
> find identifiers, something that shouldn't happen with those more
> powerful facilities.

Nothing is perfect, and I'm sure there will be cases when a user sees a 
search fail using one of these more advanced systems. The right course 
of action there would be to refine their configuration and/or report 
bugs to appropriate places, and only then maybe try etags (which could 
still produce worse results).

Anyway, I don't have any significant improvements to suggest over the 
current wording, in this regard.

> Thanks, but I see no reason to cloud the issue by refraining from
> clearly identifying the situation where this command could be useful.
> So I changed the text to make it more accurate, in the hope that it
> will no longer lend itself to interpretation that prompted your
> reaction.

It's better, thank you.

Also after re-reading, I see some duplication with what's been said 
before about how a backend can implement its capabilities in different 
ways ("built-in means for looking up"), that first item already lists 
the disadvantages. BTW, you mentioned the auto-loaded functions in the 
new description of xref-etags-mode, but not in the aforementioned 
section above, which is arguably more important.

Anyway, these are minor things, and I don't have any concrete proposals 
here.