Highlighting a missing final newline?

Highlighting a missing final newline?

[egarrulo]

How would you highlight a missing final newline?  I mean: if a buffer 
lacks a final newline, then you would see a (customizable) character at 
the end of the buffer; otherwise, you would see nothing.

AFAIK, `font-lock-add-keywords' can't help here because there is no 
character to highlight.  I have looked into `whitespace-mode' for 
inspiration, but the code is too complex for me.

Thank you.

Re: Highlighting a missing final newline?

[Yuri Khan]

On Tue, Mar 22, 2016 at 5:30 PM, egarrulo <egarrulo@gmail.com> wrote:
> How would you highlight a missing final newline?  I mean: if a buffer lacks
> a final newline, then you would see a (customizable) character at the end of
> the buffer; otherwise, you would see nothing.
>
> AFAIK, `font-lock-add-keywords' can't help here because there is no
> character to highlight.  I have looked into `whitespace-mode' for
> inspiration, but the code is too complex for me.
>
> Thank you.

Maybe highlight the last character which is not newline and is
immediately followed by the end of buffer, by regexp ".\'"?

Re: Highlighting a missing final newline?

[egarrulo]

On 22/03/16 12:50, Yuri Khan wrote:
> Maybe highlight the last character which is not newline and is
> immediately followed by the end of buffer, by regexp ".\'"?

I had considered this solution, but this way it seems that there is 
something wrong with the last printable character.  Thanks anyway.

RE: Highlighting a missing final newline?

[Drew Adams]

> How would you highlight a missing final newline?  I mean: if a buffer
> lacks a final newline, then you would see a (customizable) character at
> the end of the buffer; otherwise, you would see nothing.
> 
> AFAIK, `font-lock-add-keywords' can't help here because there is no
> character to highlight.  I have looked into `whitespace-mode' for
> inspiration, but the code is too complex for me.

I suppose you already know about option `require-final-newline',
and you really want highlighting, not just a chance to add a final
newline.  If not:

---

require-final-newline is a variable defined in ‘files.el’.
Its value is nil

  This variable is safe as a file local variable if its value
  satisfies the predicate ‘symbolp’.

Whether to add a newline automatically at the end of the file.

A value of t means do this only when the file is about to be saved.
A value of ‘visit’ means do this right after the file is visited.
A value of ‘visit-save’ means do it at both of those times.
Any other non-nil value means ask user whether to add a newline, when saving.
A value of nil means don’t add newlines.

Certain major modes set this locally to the value obtained
from ‘mode-require-final-newline’.

You can customize this variable.

Re: Highlighting a missing final newline?

[egarrulo]

On 22/03/16 14:49, Drew Adams wrote:
> I suppose you already know about option `require-final-newline',
> and you really want highlighting, not just a chance to add a final
> newline.

Yes, I do know about `require-final-newline'.  Thanks.

Re: Highlighting a missing final newline?

[Óscar Fuentes]

egarrulo <egarrulo@gmail.com> writes:

> How would you highlight a missing final newline?  I mean: if a buffer
> lacks a final newline, then you would see a (customizable) character
> at the end of the buffer; otherwise, you would see nothing.
>
> AFAIK, `font-lock-add-keywords' can't help here because there is no
> character to highlight.  I have looked into `whitespace-mode' for
> inspiration, but the code is too complex for me.

If your problem consists on editing files that require to end with a
newline, set `require-final-newline' on the mode hook and forget about
that.

Re: Highlighting a missing final newline?

[Eli Zaretskii]

> From: egarrulo <egarrulo@gmail.com>
> Date: Tue, 22 Mar 2016 12:30:45 +0100
> 
> How would you highlight a missing final newline?  I mean: if a buffer 
> lacks a final newline, then you would see a (customizable) character at 
> the end of the buffer; otherwise, you would see nothing.

Did you try to enable the indicate-buffer-boundaries feature?

Re: Highlighting a missing final newline?

[egarrulo]

On 22/03/16 17:21, Eli Zaretskii wrote:
>> From: egarrulo <egarrulo@gmail.com>
>> Date: Tue, 22 Mar 2016 12:30:45 +0100
>>
>> How would you highlight a missing final newline?  I mean: if a buffer
>> lacks a final newline, then you would see a (customizable) character at
>> the end of the buffer; otherwise, you would see nothing.
>
> Did you try to enable the indicate-buffer-boundaries feature?

This.  Thanks.