Support priority of event handlers

1 files changed, 11 insertions, 3 deletions

diff --git a/sphinx/application.py b/sphinx/application.py
index 515d962dc..fbc637e60 100644
--- a/sphinx/application.py
+++ b/sphinx/application.py
@@ -404,17 +404,25 @@ class Sphinx:
             raise VersionRequirementError(version)
 
     # event interface
-    def connect(self, event: str, callback: Callable) -> int:
+    def connect(self, event: str, callback: Callable, priority: int = 500) -> int:
         """Register *callback* to be called when *event* is emitted.
 
         For details on available core events and the arguments of callback
         functions, please see :ref:`events`.
 
+        Registered callbacks will be invoked on event in the order of *priority* and
+        registration.  The priority is ascending order.
+
         The method returns a "listener ID" that can be used as an argument to
         :meth:`disconnect`.
+
+        .. versionchanged:: 3.0
+
+           Support *priority*
         """
-        listener_id = self.events.connect(event, callback)
-        logger.debug('[app] connecting event %r: %r [id=%s]', event, callback, listener_id)
+        listener_id = self.events.connect(event, callback, priority)
+        logger.debug('[app] connecting event %r (%d): %r [id=%s]',
+                     event, priority, callback, listener_id)
         return listener_id
 
     def disconnect(self, listener_id: int) -> None: