diff options
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/lispref/text.texi | 30 |
1 files changed, 18 insertions, 12 deletions
diff --git a/doc/lispref/text.texi b/doc/lispref/text.texi index de0b00758a..8b4810f4a6 100644 --- a/doc/lispref/text.texi +++ b/doc/lispref/text.texi @@ -4687,18 +4687,20 @@ will interfere in bizarre ways with the editing operations that call them. @defvar before-change-functions -This variable holds a list of functions to call before most buffer -modifications. Each function gets two arguments, the beginning and end -of the region that is about to change, represented as integers. The -buffer that is about to change is always the current buffer. +This variable holds a list of functions to call when Emacs is about to +modify a buffer. Each function gets two arguments, the beginning and +end of the region that is about to change, represented as integers. +The buffer that is about to change is always the current buffer when +the function is called. @end defvar @defvar after-change-functions -This variable holds a list of functions to call after any buffer -modification. Each function receives three arguments: the beginning -and end of the region just changed, and the length of the text that -existed before the change. All three arguments are integers. The -buffer that has been changed is always the current buffer. +This variable holds a list of functions to call after Emacs modifies a +buffer. Each function receives three arguments: the beginning and end +of the region just changed, and the length of the text that existed +before the change. All three arguments are integers. The buffer that +has been changed is always the current buffer when the function is +called. The length of the old text is the difference between the buffer positions before and after that text as it was before the change. As @@ -4712,9 +4714,13 @@ as changes in buffers created by Emacs internally for certain jobs, that should not be visible to Lisp programs. Do @emph{not} expect the before-change hooks and the after-change -hooks be called in balanced pairs around each buffer change. These -hooks are provided on the assumption that Lisp programs will use -either before- or the after-change hooks, but not both. +hooks be called in balanced pairs around each buffer change. Also +don't expect the before-change hooks to be called for every chunk of +text Emacs is about to delete. These hooks are provided on the +assumption that Lisp programs will use either before- or the +after-change hooks, but not both, and the boundaries of the region +where the changes happen might include more than just the actual +changed text, or even lump together several changes done piecemeal. @defmac combine-after-change-calls body@dots{} The macro executes @var{body} normally, but arranges to call the |