Support cached_property on object with __slots__

Closes #12894

modules/edocument_uncefact/edocument.py

@@ -53,7 +53,7 @@ def remove_comment(stream):
 class Invoice(Model):
     "EDocument UN/CEFACT Invoice"
     __name__ = 'edocument.uncefact.invoice'
-    __no_slots__ = True  # to work with cached_property
+    __slots__ = ('invoice',)
 
     @classmethod
     def __setup__(cls):

trytond/CHANGELOG

@@ -1,3 +1,4 @@
+* Support cached_property on object with __slots__
 * Allow creating indexes concurrently
 * Allow skipping index creation
 * Add assert methods to test tools

trytond/trytond/model/model.py

@@ -32,7 +32,9 @@ class Model(URLMixin, PoolBase, metaclass=ModelMeta):
     """
     Define a model in Tryton.
     """
-    __slots__ = ('_id', '_values', '_init_values', '_removed', '_deleted')
+    __slots__ = (
+        '_id', '_values', '_init_values', '_removed', '_deleted',
+        '__weakref__')
     _rec_name = 'name'
 
     id = fields.Integer(lazy_gettext('ir.msg_ID'), readonly=True)

trytond/trytond/tests/test_tools.py

@@ -12,8 +12,8 @@ import sql
 import sql.operators
 
 from trytond.tools import (
-    decimal_, escape_wildcard, file_open, firstline, grouped_slice,
-    is_full_text, is_instance_method, likify, lstrip_wildcard,
+    cached_property, decimal_, escape_wildcard, file_open, firstline,
+    grouped_slice, is_full_text, is_instance_method, likify, lstrip_wildcard,
     pairwise_longest, reduce_domain, reduce_ids, remove_forbidden_chars,
     rstrip_wildcard, slugify, sortable_values, strip_wildcard, timezone,
     unescape_wildcard)
@@ -1214,6 +1214,58 @@ class QRCodeTestCase(unittest.TestCase):
         self.assertIsNotNone(image.getvalue())
 
 
+class CachedProperty:
+    _count = 0
+
+    def get_count(self):
+        self._count += 1
+        return self._count
+
+    cached_count = cached_property(get_count)
+
+
+class CachedPropertySlots:
+    __slots__ = ('_count', '__weakref__')
+
+    def __init__(self):
+        self._count = 0
+
+    def get_count(self):
+        self._count += 1
+        return self._count
+
+    cached_count = cached_property(get_count)
+
+
+class CachedPropertyTestCase(unittest.TestCase):
+    "Test cached_property"
+
+    def test_cached_property_clear(self):
+        "Test clear cached property"
+        item = CachedProperty()
+
+        self.assertEqual(item.cached_count, 1)
+        del item.cached_count
+        self.assertEqual(item.cached_count, 2)
+
+    def test_cached_property_with_slots(self):
+        "Test cached property with slots"
+        item = CachedPropertySlots()
+
+        self.assertEqual(item.cached_count, 1)
+        self.assertEqual(item.cached_count, 1)
+        self.assertEqual(item.get_count(), 2)
+        self.assertEqual(item.cached_count, 1)
+
+    def test_cached_property_with_slots_clear(self):
+        "Test clear cached property with slots"
+        item = CachedPropertySlots()
+
+        self.assertEqual(item.cached_count, 1)
+        del item.cached_count
+        self.assertEqual(item.cached_count, 2)
+
+
 def load_tests(loader, tests, pattern):
     tests.addTest(doctest.DocTestSuite(decimal_))
     return tests

trytond/trytond/tools/__init__.py

@@ -1,11 +1,8 @@
 # This file is part of Tryton.  The COPYRIGHT file at the top level of
 # this repository contains the full copyright notices and license terms.
 import posixpath
-
-try:
-    from functools import cached_property
-except ImportError:
-    from werkzeug.utils import cached_property
+from functools import cached_property
+from weakref import WeakKeyDictionary
 
 try:
     from werkzeug.security import safe_join
@@ -21,6 +18,36 @@ from .misc import (
     rstrip_wildcard, slugify, sortable_values, sql_pairing, strip_wildcard,
     unescape_wildcard)
 
+_NOT_FOUND = object()
+
+
+class cached_property(cached_property):
+    _cache = None
+
+    def __get__(self, instance, owner=None):
+        if instance is None:
+            return self
+        cache = getattr(instance, '__dict__', None)
+        if cache is None:  # __slots__
+            if self._cache is None:
+                self._cache = WeakKeyDictionary()
+            val = self._cache.get(instance, _NOT_FOUND)
+            if val is _NOT_FOUND:
+                self._cache[instance] = val = self.func(instance)
+            return val
+        else:
+            return super().__get__(instance, owner)
+
+    def __delete__(self, instance):
+        cache = getattr(instance, '__dict__', None)
+        try:
+            if cache:
+                del cache[self.attrname]
+            elif self._cache:
+                del self._cache[instance]
+        except KeyError:
+            pass
+
 
 class ClassProperty(property):
     def __get__(self, cls, owner):