Simplify @pyside_cache decorator

This fixes a compatibility issue with Python 3.9+, and at the same time
avoids a not-yet-quite-stable area of Blender's Python API.

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Blender Cloud changelog
 
+## Version 1.19 (in development)
+
+- Another Python 3.9+ compatibility fix.
+
 ## Version 1.18 (2021-02-16)
 
 - Add compatibility with Python 3.9 (as used in Blender 2.93).

blender_cloud/blender.py

@@ -47,7 +47,7 @@ log = logging.getLogger(__name__)
 icons = None
 
 
-@pyside_cache("version")
+@pyside_cache
 def blender_syncable_versions(self, context):
     """Returns the list of items used by SyncStatusProperties.version EnumProperty."""
 
@@ -117,7 +117,7 @@ class SyncStatusProperties(PropertyGroup):
         self["available_blender_versions"] = new_versions
 
 
-@pyside_cache("project")
+@pyside_cache
 def bcloud_available_projects(self, context):
     """Returns the list of items used by BlenderCloudProjectGroup.project EnumProperty."""
 

blender_cloud/flamenco/__init__.py

@@ -91,7 +91,7 @@ def scene_sample_count(scene) -> int:
     return samples
 
 
-@pyside_cache("manager")
+@pyside_cache
 def available_managers(self, context):
     """Returns the list of items used by a manager-selector EnumProperty."""
 

blender_cloud/utils.py

@@ -19,6 +19,7 @@
 import json
 import pathlib
 import typing
+from typing import Any, Dict, Optional, Tuple
 
 
 def sizeof_fmt(num: int, suffix="B") -> str:
@@ -35,7 +36,7 @@ def sizeof_fmt(num: int, suffix="B") -> str:
     return "%.1f Yi%s" % (num, suffix)
 
 
-def find_in_path(path: pathlib.Path, filename: str) -> typing.Optional[pathlib.Path]:
+def find_in_path(path: pathlib.Path, filename: str) -> Optional[pathlib.Path]:
     """Performs a breadth-first search for the filename.
 
     Returns the path that contains the file, or None if not found.
@@ -66,41 +67,29 @@ def find_in_path(path: pathlib.Path, filename: str) -> typing.Optional[pathlib.P
     return None
 
 
-def pyside_cache(propname):
+# Mapping from (module name, function name) to the last value returned by that function.
+_pyside_cache: Dict[Tuple[str, str], Any] = {}
+
+
+def pyside_cache(wrapped):
     """Decorator, stores the result of the decorated callable in Python-managed memory.
 
     This is to work around the warning at
     https://www.blender.org/api/blender_python_api_master/bpy.props.html#bpy.props.EnumProperty
     """
 
-    if callable(propname):
+    import functools
-        raise TypeError('Usage: pyside_cache("property_name")')
 
-    def decorator(wrapped):
+    @functools.wraps(wrapped)
-        """Stores the result of the callable in Python-managed memory.
+    # We can't use (*args, **kwargs), because EnumProperty explicitly checks
-
+    # for the number of fixed positional arguments.
-        This is to work around the warning at
+    def decorator(self, context):
-        https://www.blender.org/api/blender_python_api_master/bpy.props.html#bpy.props.EnumProperty
+        result = None
-        """
+        try:
-
+            result = wrapped(self, context)
-        import functools
+            return result
-
+        finally:
-        @functools.wraps(wrapped)
+            _pyside_cache[wrapped.__module__, wrapped.__name__] = result
-        # We can't use (*args, **kwargs), because EnumProperty explicitly checks
-        # for the number of fixed positional arguments.
-        def wrapper(self, context):
-            result = None
-            try:
-                result = wrapped(self, context)
-                return result
-            finally:
-                try:
-                    rna_type, rna_info = self.bl_rna.__annotations__[propname]
-                except AttributeError:
-                    rna_type, rna_info = getattr(self.bl_rna, propname)
-                rna_info["_cached_result"] = result
-
-        return wrapper
 
     return decorator