From d885b4333f18591ddccdf2bb28fdae2f772589af Mon Sep 17 00:00:00 2001
From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Fri, 20 Nov 2020 14:34:40 -0500
Subject: apply staticmethod() to pickle.dumps/loads as class variables

Fixed regression where the serialization and deserialization functions
could be inadvertently turned into instance methods with an unexpected
argument signature, namely when pickle.dumps and pickle.loads are the pure
Python version as is the case in pypy.

Fixes: #195
Change-Id: Ie8b332510a1d5d0a6c34ed4338f2a71e327676a8
---
 docs/build/unreleased/195.rst |  9 +++++++++
 dogpile/cache/api.py          | 12 ++++++++----
 2 files changed, 17 insertions(+), 4 deletions(-)
 create mode 100644 docs/build/unreleased/195.rst

diff --git a/docs/build/unreleased/195.rst b/docs/build/unreleased/195.rst
new file mode 100644
index 0000000..e7ba8f4
--- /dev/null
+++ b/docs/build/unreleased/195.rst
@@ -0,0 +1,9 @@
+.. change::
+    :tags: bug, region
+    :tickets: 195
+
+    Fixed regression where the serialization and deserialization functions
+    could be inadvertently turned into instance methods with an unexpected
+    argument signature, namely when pickle.dumps and pickle.loads are the pure
+    Python version as is the case in pypy.
+
diff --git a/dogpile/cache/api.py b/dogpile/cache/api.py
index d89ac56..3d6bfa4 100644
--- a/dogpile/cache/api.py
+++ b/dogpile/cache/api.py
@@ -141,7 +141,7 @@ class CacheBackend:
 
     """
 
-    serializer: Optional[Serializer] = None
+    serializer: Union[None, Serializer, staticmethod] = None
     """Serializer function that will be used by default if not overridden
     by the region.
 
@@ -149,7 +149,7 @@ class CacheBackend:
 
     """
 
-    deserializer: Optional[Deserializer] = None
+    deserializer: Union[None, Deserializer, staticmethod] = None
     """deserializer function that will be used by default if not overridden
     by the region.
 
@@ -435,8 +435,12 @@ class CacheBackend:
 
 
 class DefaultSerialization:
-    serializer: Optional[Serializer] = pickle.dumps
-    deserializer: Optional[Deserializer] = pickle.loads
+    serializer: Union[None, Serializer, staticmethod] = staticmethod(
+        pickle.dumps
+    )
+    deserializer: Union[None, Deserializer, staticmethod] = staticmethod(
+        pickle.loads
+    )
 
 
 class BytesBackend(DefaultSerialization, CacheBackend):
-- 
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