Re: Lisp primitives and their calling of the change hooks

[Eli Zaretskii <eliz@gnu.org>]

> Date: Thu, 4 Jan 2018 21:11:54 +0000
> From: Alan Mackenzie <acm@muc.de>
> Cc: emacs-devel@gnu.org
> 
>     The primitives which atomically insert or delete a contiguous chunk
>     of text into or from a buffer will call `before-change-functions'
>     and `after-change-functions' in balanced pairs, once for each
>     change.  The arguments to these hooks will exactly delimit the
>     change being made.  Calls to these primitives comprise the vast bulk
>     of buffer changes.
> 
>     Other, more complex primitives aim to call `before-change-functions'
>     once before making any changes, then to call
>     `after-change-functions' zero, one, or several times, depending on
>     how many individual changes the primitive makes.  The `BEG' and
>     `END' arguments to `before-change-functions' will enclose a region
>     in which the individual changes are made, but won't necessarily be
>     the minimal such region.  The `BEG', `END', and `OLD-LEN' arguments
>     to each successive call of `after-change-functions' will accurately
>     delimit the current change.

How will the reader know to distinguish between these two classes of
primitives?  Without such an ability, the extra accuracy in this text
is not useful.