How to tell that buffer is not modifed?

How to tell that buffer is not modifed?

[Jean Louis]

I would like to tell programmatically that buffer is not modified even
though it is modified.

I am inserting the database entry into the buffer, but because
`set-auto-mode' works only on buffers with associated file names, I am
assocating a file name with revision number. This association makes
buffer look modified and killing buffer asks for saving. I would like
to tell that buffer is not modified, as the information arrived from
database and it is anyway in a read only mode.

    (switch-to-buffer (get-buffer-create buffer))
    (setq-local buffer-file-name filename-revised)
    (read-only-mode 0)
    (insert body)
    (goto-char 1)
    (set-auto-mode)
    (read-only-mode 1)))

Jean

Re: How to tell that buffer is not modifed?

[Eli Zaretskii]

> Date: Thu, 25 Mar 2021 11:53:36 +0300
> From: Jean Louis <bugs@gnu.support>
> 
> I would like to tell programmatically that buffer is not modified even
> though it is modified.

See the function set-buffer-modified-p.

Re: How to tell that buffer is not modifed?

[Jean Louis]

* Eli Zaretskii <eliz@gnu.org> [2021-03-25 12:32]:
> > Date: Thu, 25 Mar 2021 11:53:36 +0300
> > From: Jean Louis <bugs@gnu.support>
> > 
> > I would like to tell programmatically that buffer is not modified even
> > though it is modified.
> 
> See the function set-buffer-modified-p.

Oh yes, thanks. 

I have tried solving it by associating the file to buffer and then
disassociating, as that way `set-auto-mode' works.

    (switch-to-buffer buffer)
    (setq-local buffer-file-name filename-revised)
    (read-only-mode 0)
    (insert body)
    (goto-char 1)
    (set-auto-mode)
    (setq-local buffer-file-name nil)
    (read-only-mode 1)

Now it seem not good idea to use it with `set-buffer-modified-p'

    (switch-to-buffer buffer)
    (setq-local buffer-file-name filename-revised)
    (read-only-mode 0)
    (insert body)
    (goto-char 1)
    (set-auto-mode)
    ;; (setq-local buffer-file-name nil) ;; TODO
    (set-buffer-modified-p nil) ;; TODO which one is better?
    (read-only-mode 1)

as then if I wish to save the associated file but buffer is not
modified, saving is not easy, as Emacs thinks it was already saved.

It is solved. 

I will let it be associated to versioned file number, if user wish to
save revision of a previous file, the associated file name is there
and user may save it.

Jean