Detect all changes in a buffer

Detect all changes in a buffer

[Lars Tveito]

Hi!

I am developing a minor mode that enables real-time collaboration. I
wish to detect /all/ changes made to a buffer. So far I'm using
`before-change-functions' to detect deletions and
`after-change-functions' to detect insertions.

The problem is that some functions utilizes
`inhibit-modification-hooks', even though they make changes to the
buffer. An example is `eshell-send-input'.

The first question is whether you have any suggestions as to how to get
around this? The second is whether it is considered OK for functions to
use this hook even though the function makes changes to the buffer? The
documentation for change hooks states "These hook variables let you
arrange to take notice of all changes in all buffers" which is not
really true if changes are done whilst `inhibit-modification-hooks' is
non-nil.

- Lars

Re: Detect all changes in a buffer

[Karl Fogel]

Lars Tveito <larstvei@ifi.uio.no> writes:
>I am developing a minor mode that enables real-time collaboration. I
>wish to detect /all/ changes made to a buffer. So far I'm using
>`before-change-functions' to detect deletions and
>`after-change-functions' to detect insertions.

You might already know about these, but just in case:

There was some work on this in the past -- the effort I remember was based on a collaboration protocol called "Obby", but now that I look at https://www.emacswiki.org/emacs/CollaborativeEditing I see there were some other efforts as well.

I don't know if anything there would save you time, but wanted to point it out just in case.

(You raise a good question about `inhibit-modification-hooks', and I don't know the answer to it.)

Best regards,
-Karl

>The problem is that some functions utilizes
>`inhibit-modification-hooks', even though they make changes to the
>buffer. An example is `eshell-send-input'.
>
>The first question is whether you have any suggestions as to how to get
>around this? The second is whether it is considered OK for functions to
>use this hook even though the function makes changes to the buffer? The
>documentation for change hooks states "These hook variables let you
>arrange to take notice of all changes in all buffers" which is not
>really true if changes are done whilst `inhibit-modification-hooks' is
>non-nil.
>
>- Lars

Re: Detect all changes in a buffer

[raman]

Karl Fogel <kfogel@red-bean.com> writes:

there was also an effort based around erlang > Lars Tveito <larstvei@ifi.uio.no> writes:
>>I am developing a minor mode that enables real-time collaboration. I
>>wish to detect /all/ changes made to a buffer. So far I'm using
>>`before-change-functions' to detect deletions and
>>`after-change-functions' to detect insertions.
>
> You might already know about these, but just in case:
>
> There was some work on this in the past -- the effort I remember was based on a collaboration protocol called "Obby", but now that I look at https://www.emacswiki.org/emacs/CollaborativeEditing I see there were some other efforts as well.
>
> I don't know if anything there would save you time, but wanted to point it out just in case.
>
> (You raise a good question about `inhibit-modification-hooks', and I don't know the answer to it.)
>
> Best regards,
> -Karl
>
>>The problem is that some functions utilizes
>>`inhibit-modification-hooks', even though they make changes to the
>>buffer. An example is `eshell-send-input'.
>>
>>The first question is whether you have any suggestions as to how to get
>>around this? The second is whether it is considered OK for functions to
>>use this hook even though the function makes changes to the buffer? The
>>documentation for change hooks states "These hook variables let you
>>arrange to take notice of all changes in all buffers" which is not
>>really true if changes are done whilst `inhibit-modification-hooks' is
>>non-nil.
>>
>>- Lars
>

-- 

Re: Detect all changes in a buffer

[Stefan Monnier]

> There was some work on this in the past -- the effort I remember was based
> on a collaboration protocol called "Obby", but now that I look at
> https://www.emacswiki.org/emacs/CollaborativeEditing I see there were some
> other efforts as well.

GNU ELPA has Rudel which indeed supports the Obby protocol.

> (You raise a good question about `inhibit-modification-hooks', and
>  I don't know the answer to it.)

Making "real" modifications to the buffer while binding
inhibit-modification-hooks to a non-nil value sounds like a bug.

BTW, after-change-functions should work just as well for deletions as
for insertions.


        Stefan