New property dynamic-docstring-function for docstrings.

* src/doc.c (Fdocumentation): Handle new property
dynamic-docstring-function to replace the old ad-advice-info.
* lisp/emacs-lisp/advice.el: Use new dynamic docstrings.
(ad-make-advised-definition-docstring, ad-advised-definition-p):
Use dynamic-docstring-function instead of ad-advice-info.
(ad--make-advised-docstring): New function extracted from
ad-make-advised-docstring.
(ad-make-advised-docstring): Use it.
* lisp/progmodes/sql.el (sql--make-help-docstring): New function, extracted
from sql-help.
(sql-help): Use it with dynamic-docstring-function.

1 files changed, 4 insertions, 0 deletions

diff --git a/etc/NEWS b/etc/NEWS
index 2b56ea9f540..bb8bcd6cb56 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -29,6 +29,10 @@ so we will look at it and add it to the manual.
 * New Modes and Packages in Emacs 24.4
 * Incompatible Lisp Changes in Emacs 24.4
 * Lisp changes in Emacs 24.4
+
+** Docstrings can be made dynamic by adding a `dynamic-docstring-function'
+text-property on the first char.
+
 * Changes in Emacs 24.4 on non-free operating systems