Re: before-change-functions called twice at yank

[martin rudalics <rudalics@gmx.at>]

> Do emacs -q and evaluate
>
> (progn
>   (add-hook 'before-change-functions
>             (lambda (b e)
>               (message "before-change: '%s'" (buffer-substring b e))) nil t)
>   (add-hook 'after-change-functions
>             (lambda (b e l)
>               (message "after-change: '%s'" (buffer-substring b e))) nil t))
>
>
> in the *scratch* buffer. If you press the letter a, the message buffer
> will get
>
> before-change: ''
> after-change: 'a'
>
> as expected. Now yank the string "foo". Then the message buffer gets
>
> before-change: ''
> after-change: 'foo'
> before-change: 'foo'
>
> This seems as a bug to me. Am I missing something?

Indeed you should see another message from `after-change-functions' like:

before-change: ''
after-change: 'foo'
before-change: 'foo'
after-change: 'foo'

The last two messages are due to `remove-yank-excluded-properties' which
removes `yank-excluded-properties' from the string inserted.  You can
avoid running the hooks either by doing

   (let ((inhibit-read-only t)
	(inhibit-modification-hooks t))

in `remove-yank-excluded-properties' directly or by wrapping the calls to
`remove-yank-excluded-properties' in `insert-for-yank-1' (and possibly
`insert-buffer-substring-as-yank') as

   (let ((inhibit-modification-hooks t))	
      (remove-yank-excluded-properties opoint (point)))