Re: Overlay arrow in *compilation* and *grep* buffers

[Juri Linkov <juri@jurta.org>]

> Currently simple.el has:
>
> (put 'next-error-overlay-arrow-position 'overlay-arrow-string "=>")
>
> but this could be removed as it is the default now anyway (I think Juri
> disappeared again before 2005-04-08).

Sorry.  I traveled to my friend.  She lives 1000km from me.

> I suggest this latter change until Juri (or maybe Stefan) comes up with a
> better solution that will work with "=>".

I suggest adding a new option defining how to highlight lines
in compilation/grep buffers, similar to `next-error-highlight'
which defines highlighting in source buffers.  It will replace
`compilation-context-lines':

(defcustom compilation-message-highlight 0
  "*Highlighting of locations in the compilation buffer.
If number, display this many lines of leading context before message.
If t, use persistent overlays fontified in next-error face.
If nil, don't highlight the locus in the compilation buffer.
If `fringe-arrow', indicate the locus by the fringe arrow."
  :type '(choice (number :tag "Context lines")
                 (const :tag "Persistent overlay" t)
                 (const :tag "No highlighting" nil)
                 (const :tag "Fringe arrow" 'fringe-arrow))
  :group 'compilation
  :version "22.1")

Since the number of context lines and fringe arrow are mutually exclusive
values, there will be no problem with an arrow overlapping a file name
in the compilation buffer, because by default there will be no arrow at all.
Users wishing to use arrows can set `compilation-message-highlight' to
`fringe-arrow' in .emacs conditionally depending on the presence of fringes.

BTW, I don't understand the reason of adding `(defvar next-error-highlight-timer)'
to compile.el on 2005-04-23.  There is already the same defvar in simple.el.

-- 
Juri Linkov
http://www.jurta.org/emacs/