Add highlight-symbol-nav-mode

[swsnr]

This minor mode binds highlight-symbol-prev and highlight-symbol-next to M-p
and M-n respectively.

It is not particularly advanced, but quite convenient.

[purcell]

Would be nice to have a globalized variant of this too.

[swsnr]

@purcell I'll add one, if @nschum is generally willing to accept this feature.

[purcell]

I'm a big fan of wrapping groups of related interactive functions into minor mode + global minor mode pairs. Seems to give the best blend of flexibility and convenience.

[swsnr]

@purcell I'm as well :), but @nschum might think differently :)

[nschum]

While I'm not a fan of such groupings, I don't mind adding it by popular demand. :)

I'm not opposed to a global mode, either, but could there be any problems in special buffers? (See my concerns in #11.)

[swsnr]

@nschum I don't know, whether there could be problems. It is possible to inhibit a global mode in specific buffers, but I have no clue, what prerequisites a buffer must fulfill to be compatible with symbol navigation. I haven't looked at the source of these functions.

Shouldn't you know which modes are incompatible?

[nschum]

Well, as I said in #11: I only enable the keybindings in coding modes, so I haven't really tested anywhere else. I also generally don't use global modes.

Before merging a global mode, I'd like to know it's been tested a bit so there aren't any surprises.

[nschum]

I guess merging the commit automatically closes the PR. That's not an indication I've decided against a global mode. :)

[purcell]

You're right that hooking prog-mode would get us most of the way there. The main thing is to have a nice specific keymap for the mode.

As far as default restrictions for global modes go, I find this a fairly conservative "turn-on" function template:

(defun turn-on-my-magic-mode ()
  (unless (or (minibufferp)
              (derived-mode-p 'special-mode 'view-mode 'comint-mode))
    (my-magic-mode 1)))

[purcell]

But @lunaryorn or I can now easily try a globalized version of this minor mode locally and see if it makes sense. So thanks for merging. :-)

[swsnr]

@nschum Thank you :)