bpo-40988: Optimized singledispatchmethod access.

python · AlexWaygood · Aug 6, 2023 · Nov 10, 2020 · Jul 5, 2023 · Jul 23, 2023
commit 04fe64e5c261688149c28cb56db71f13d51dc8b5
@@ -901,6 +901,7 @@ def __init__(self, func):
 
         self.dispatcher = singledispatch(func)
         self.func = func
+        self.attrname = None
 
     def register(self, cls, method=None):
         """generic_method.register(cls, func) -> func
@@ -909,6 +910,9 @@ def register(self, cls, method=None):
         """
         return self.dispatcher.register(cls, func=method)
 
+    def __set_name__(self, _, name):
+        self.attrname = name
+
     def __get__(self, obj, cls=None):
         def _method(*args, **kwargs):
             method = self.dispatcher.dispatch(args[0].__class__)
@@ -917,6 +921,15 @@ def _method(*args, **kwargs):
         _method.__isabstractmethod__ = self.__isabstractmethod__
         _method.register = self.register
         update_wrapper(_method, self.func)
+
+        if self.attrname is not None:
+            attrname = self.attrname
+
+            try:
+                obj.__dict__[attrname] = _method
+            except AttributeError:
+                pass  # not all objects have __dict__ (e.g. class defines slots)
+
         return _method
 
     @property

diff --git a/Misc/NEWS.d/next/Library/2020-11-10-07-04-15.bpo-40988.5kBC-O.rst b/Misc/NEWS.d/next/Library/2020-11-10-07-04-15.bpo-40988.5kBC-O.rst
@@ -0,0 +1,2 @@
+Applied a cached_propery type optimization suggested by federico to
+singledispatchmethod yielding approximately a 3.5 speedup in access times.
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Applied a cached_propery type optimization suggested by federico to
		singledispatchmethod yielding approximately a 3.5 speedup in access times.