Allow for custom URL handlers in browse-url.

* lisp/net/browse-url.el (browse-url-handlers): New defcustom.
(browse-url-default-handlers): New defvar.
(browse-url): Use them.  Adapt docstring.  Issue a warning pointing to
browse-url-handlers when browse-url-browser-function is an alist.
(browse-url--mailto, browse-url--man): New functions.
(browse-url--browser-defcustom-type): Add :doc that the alist usage is
deprecated.
(browse-url-browser-function): Remove documentation referring to the
alist usage and mention browse-url-handlers.
* doc/emacs/misc.texi: Document browse-url-handlers in Browse-URL
node.
* etc/NEWS: Mention browse-url-default-handlers and
browse-url-handlers.

1 files changed, 10 insertions, 3 deletions

diff --git a/doc/emacs/misc.texi b/doc/emacs/misc.texi
index 47f195d0b20..d1854f31ff3 100644
--- a/doc/emacs/misc.texi
+++ b/doc/emacs/misc.texi
@@ -2920,9 +2920,16 @@ you might like to bind to keys, such as @code{browse-url-at-point} and
   You can customize Browse-URL's behavior via various options in the
 @code{browse-url} Customize group.  In particular, the option
 @code{browse-url-mailto-function} lets you define how to follow
-@samp{mailto:} URLs, while @code{browse-url-browser-function} lets you
-define how to follow other types of URLs.  For more information, view
-the package commentary by typing @kbd{C-h P browse-url @key{RET}}.
+@samp{mailto:} URLs, while @code{browse-url-browser-function}
+specifies your default browser.
+
+@vindex browse-url-handlers
+  You can define that certain URLs are browsed with other functions by
+customizing @code{browse-url-handlers}, an alist of regular
+expressions paired with functions to browse matching URLs.
+
+For more information, view the package commentary by typing @kbd{C-h P
+browse-url @key{RET}}.
 
 @node Goto Address mode
 @subsection Activating URLs