pickler: Cython 3.0 compatibility

CHANGES.rst

@@ -1,5 +1,6 @@
 v3.0.3
 ======
+    * Compatibilty with Pandas and Cython 3.0 was added. (#460) (+477)
     * Fixed a bug where pickling some built-in classes (e.g. zoneinfo) 
       could return a ``None`` module. (#447)
     * Fixed a bug where unpickling a missing class would return a different object

jsonpickle/pickler.py

@@ -803,15 +803,15 @@ def _get_flattener(self, obj):
                 else tags.SET: [self._flatten(v) for v in obj]
             }
 
+        elif util.is_module_function(obj):
+            return self._flatten_function
+
         elif util.is_object(obj):
             return self._ref_obj_instance
 
         elif util.is_type(obj):
             return _mktyperef
 
-        elif util.is_module_function(obj):
-            return self._flatten_function
-
         # instance methods, lambdas, old style classes...
         self._pickle_warning(obj)
         return None

jsonpickle/util.py

@@ -301,7 +301,7 @@ def is_module_function(obj):
         and hasattr(obj, '__module__')
         and hasattr(obj, '__name__')
         and obj.__name__ != '<lambda>'
-    )
+    ) or is_cython_function(obj)
 
 
 def is_module(obj):
@@ -388,6 +388,15 @@ def is_reducible(obj):
     return True
 
 
+def is_cython_function(obj):
+    """Returns true if the object is a reference to a Cython function"""
+    return (
+        callable(obj)
+        and hasattr(obj, '__repr__')
+        and repr(obj).startswith('<cyfunction ')
+    )
+
+
 def in_dict(obj, key, default=False):
     """
     Returns true if key exists in obj.__dict__; false if not in.