Re: Automatic narrowing in Emacs?

[David Sumbler]

-----Original Message-----
From: David Kastrup <address@hidden>
To: David Sumbler <address@hidden>
CC: address@hidden
Subject: Re: Automatic narrowing in Emacs?
Date: Wed, 02 Jan 2019 15:14:29 +0100

David Sumbler <address@hidden> writes:

> I now realise that in these cases the buffer has been "narrowed".
> This is a useful feature of Emacs that I wasn't even aware of
> previously, and no doubt I shall start to use it intentionally in
> future.
> 
> But I find that a large buffer gets narrowed automatically when I am
> editing, even though I have not given a command for this.  Even if I
> then issue a 'widen' command (Ctrl-x n w) the buffer gets narrowed
> again after short while.

The key sequences for narrowing are _disabled_ by default as narrowing
is confusing.  If you haven't enabled them, this should not be an
issue.

Looking at LilyPond-mode, I see a few occurences of narrowing:

$ git grep narrow
lilypond-indent.el:      (narrow-to-region
lilypond-mode.el:      (narrow-to-region start end)
lilypond-song.el:          (narrow-to-region (or (mark) (point))
(point)))

Those are likely for purely programmatic reasons.  If you are plagued
here, you may want to review the respective Elisp passages to see if
the narrow-to-region sequences are reliably reversed (by being encapsulated in 
constructs that are guaranteed to restore the state of narrowing even when 
exited in error cases).

-----Original Message-----
From: Andrew Bernard <address@hidden>
To: lilypond-user Mailinglist <address@hidden>
Subject: Re: Automatic narrowing in Emacs?
Date: Wed, 2 Jan 2019 23:33:47 +1100

Hi David,

Never heard of this being automatic. Have you got a lot of
customisations in your emacs? What version are you running (not that I
think that makes any difference) and on what platform?

Weird. hard to imagine how you would have both set a mark and typed C-x 
n n inadvertently.

I always found lilypond mode a bit strange. I don't use it. Can't think
of any examples at the moment, but I understand it's a bit half baked,
isn't that so?

----------------------------------

To answer Andrew first, I am running Emacs 25.2.2 in Ubuntu 18.04.  My
own customisations of Emacs are fairly normal and trivial (screen and
font colour etc.).

And David is quite right: if I type C-x n n I get told that narrowing
is disabled, and would have to choose to enable it.  I am pretty sure
that I am cannot be typing C-x n n SPC or C-x n n ! by accident.

In other words, my buffer is being narrowed even when the narrowing
commands themselves are disabled.  Pretty mysterious, eh?

I had already looked at those 3 mentions of narrowing in the Lilypond-
mode files.  From what I could see they wouldn't cause narrowing by
accident, although I am not capable of analysing the code to the extent
that David suggests in his final sentence.

As for Lilypond-mode being half-baked, I don't find that, although
there are a few anomalies, e.g. indenting after manual beams and
sometimes after slurs is a bit buggy.  (I don't think the characters
'()[]' should affect the indenting at all in pure Lilypond code, but
occasionally they do.)  And I add 'q' to the list of allowable note-
names in lilypond-words.el so that repeated chords don't stand out like
lighthouses in the text!

David