[Emacs-diffs] master 8c17995: Fix documentation of inhibit-modification-hooks in overlays + text properties

[Alan Mackenzie]

branch: master
commit 8c17995f7f948955c765562f32526d0a3b87398e
Author: Alan Mackenzie <address@hidden>
Commit: Alan Mackenzie <address@hidden>

    Fix documentation of inhibit-modification-hooks in overlays + text 
properties
    
    This fixes bug #25111.
    
    * doc/lispref/display.text (Overlay Properties): For the hook property
    modification-hooks, state that inhibit-modification-hooks is bound to 
non-nil
    when calling its functions.  This also applies to insert-in-front-hooks and
    insert-behind-hooks, which refer to modification-hooks.
    
    * doc/lispref/text.texi (Special Properties): For the hook property
    modification-hooks, state that inhibit-modification-hooks is NOT bound to
    non-nil when calling its functions.  For the hooks insert-in-fron-hooks and
    insert-behind-hooks, state that that variable does get bound to non-nil.
---
 doc/lispref/display.texi |  9 ++++++---
 doc/lispref/text.texi    | 21 +++++++++++++++++----
 2 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/doc/lispref/display.texi b/doc/lispref/display.texi
index 7e8abb0..217df3b 100644
--- a/doc/lispref/display.texi
+++ b/doc/lispref/display.texi
@@ -1752,9 +1752,12 @@ modified, and the length of the pre-change text replaced 
by that range.
 length is the number of characters deleted, and the post-change
 beginning and end are equal.)
 
-If these functions modify the buffer, they should bind
-@code{inhibit-modification-hooks} to @code{t} around doing so, to
-avoid confusing the internal mechanism that calls these hooks.
+When these functions are called, @code{inhibit-modification-hooks} is
+bound to non-@code{nil}.  If the functions modify the buffer, you
+might want to bind @code{inhibit-modification-hooks} to @code{nil}, so
+as to cause the change hooks to run for these modifications.  However,
+doing this may call your own change hook recursively, so be sure to
+prepare for that.  @xref{Change Hooks}.
 
 Text properties also support the @code{modification-hooks} property,
 but the details are somewhat different (@pxref{Special Properties}).
diff --git a/doc/lispref/text.texi b/doc/lispref/text.texi
index 2e7c497..c4fc524 100644
--- a/doc/lispref/text.texi
+++ b/doc/lispref/text.texi
@@ -3621,9 +3621,12 @@ Furthermore, insertion will not modify any existing 
character, so this
 hook will only be run when removing some characters, replacing them
 with others, or changing their text-properties.
 
-If these functions modify the buffer, they should bind
-@code{inhibit-modification-hooks} to @code{t} around doing so, to
-avoid confusing the internal mechanism that calls these hooks.
+Unlike with other similar hooks, when Emacs calls these functions,
+@code{inhibit-modification-hooks} does @emph{not} get bound to
+non-@code{nil}.  If the functions modify the buffer, you should
+consider binding this variable to non-@code{nil} to prevent any buffer
+changes running the change hooks.  Otherwise, you must be prepared for
+recursive calls.  @xref{Change Hooks}.
 
 Overlays also support the @code{modification-hooks} property, but the
 details are somewhat different (@pxref{Overlay Properties}).
@@ -3639,6 +3642,13 @@ preceding character.  These functions receive two 
arguments, the
 beginning and end of the inserted text.  The functions are called
 @emph{after} the actual insertion takes place.
 
+When these functions are called, @code{inhibit-modification-hooks} is
+bound to non-@code{nil}.  If the functions modify the buffer, you
+might want to bind @code{inhibit-modification-hooks} to @code{nil}, so
+as to cause the change hooks to run for these modifications.  However,
+doing this may call your own change hook recursively, so be sure to
+prepare for that.
+
 See also @ref{Change Hooks}, for other hooks that are called
 when you change text in a buffer.
 
@@ -5650,5 +5660,8 @@ same hook variables, so that by default modifying the 
buffer from
 a modification hook does not cause other modification hooks to be run.
 If you do want modification hooks to be run in a particular piece of
 code that is itself run from a modification hook, then rebind locally
-@code{inhibit-modification-hooks} to @code{nil}.
+@code{inhibit-modification-hooks} to @code{nil}.  However, doing this
+may cause recursive calls to the modification hooks, so be sure to
+prepare for that (for example, by binding some variable which tells
+your hook to do nothing).
 @end defvar