bug#19468: 25.0.50; UI inconveniences with M-.

[Dmitry Gutov <dgutov@yandex.ru>]

On 05/01/2015 03:57 PM, Eli Zaretskii wrote:

> Sorry, I don't understand what "Elisp environment at runtime" means in
> practice, or how it's used to affect what results are returned for a
> query.

find-func knows about defined functions and defined variables. 
elisp-mode knows that a function usually goes after a paren, and a 
variable - after a space (to simplify things).

Thus, elisp-xref-find could narrow the search space based on whether 
there is a paren before the symbol at point (we don't do that, partially 
because the situation is more complicated; but we should, in the 
future). A language-agnostic UI won't ever be able to do so.

> That's the case where the UI should instruct the back-end what it
> needs, because the back-end doesn't know which of these alternatives
> is the right one.  If the user wants all bar functions, or maybe those
> whose parent class matches some regexp, not just the one from the
> class instance at point, then producing only one match would be wrong,
> and the UI won't be able to correct that.

If the user calls xref-find-definitions, we consider that to see the 
definition of the function called at point (or definitions, if virtual 
dispatch is unavoidable, such as in case of a Java interface, and there 
are several options), but not more.

For more lax matching options, the user will call xref-find-apropos.