[IMP] models: use slots for BaseModel

This restricts the attributes of a BaseModel instance to `env`, `_ids`
and `_prefetch_ids`.  This way, one can only assign fields on a record;
other assignments are programming errors.

This also reduces the memory footprint of records from 168 to 64 bytes
(-62%), and makes their instanciation faster.

closes odoo/odoo#51075

Related: odoo/enterprise#10529
Signed-off-by: Raphael Collet (rco) <rco@openerp.com>

4 files changed, 15 insertions, 18 deletions

diff --git a/odoo/addons/base/models/qweb.py b/odoo/addons/base/models/qweb.py
index 464cb7a166e..6a099e810bc 100644
--- a/odoo/addons/base/models/qweb.py
+++ b/odoo/addons/base/models/qweb.py
@@ -234,6 +234,7 @@ class frozendict(dict):
 
 
 class QWeb(object):
+    __slots__ = ()
 
     _void_elements = frozenset([
         'area', 'base', 'br', 'col', 'embed', 'hr', 'img', 'input', 'keygen',
diff --git a/odoo/addons/base/models/res_config.py b/odoo/addons/base/models/res_config.py
index a03a70a2ec6..1cba371e188 100644
--- a/odoo/addons/base/models/res_config.py
+++ b/odoo/addons/base/models/res_config.py
@@ -14,6 +14,8 @@ _logger = logging.getLogger(__name__)
 
 
 class ResConfigModuleInstallationMixin(object):
+    __slots__ = ()
+
     @api.model
     def _install_modules(self, modules):
         """ Install the requested modules.
diff --git a/odoo/addons/test_new_api/tests/test_attributes.py b/odoo/addons/test_new_api/tests/test_attributes.py
index 94a048f2554..27853d9a16e 100644
--- a/odoo/addons/test_new_api/tests/test_attributes.py
+++ b/odoo/addons/test_new_api/tests/test_attributes.py
@@ -1,25 +1,12 @@
 # -*- coding: utf-8 -*-
 from odoo.tests import common
 
-ANSWER_TO_ULTIMATE_QUESTION = 42
 
 class TestAttributes(common.TransactionCase):
 
-    def test_we_can_add_attributes(self):
+    def test_we_cannot_add_attributes(self):
         Model = self.env['test_new_api.category']
         instance = Model.create({'name': 'Foo'})
 
-        # assign an unknown attribute
-        instance.unknown = ANSWER_TO_ULTIMATE_QUESTION
-
-        # Does the attribute exist in the instance of the model ?
-        self.assertTrue(hasattr(instance, 'unknown'))
-
-        # Is it the right type ?
-        self.assertIsInstance(instance.unknown, int)
-
-        # Is it the right value, in case of, we don't know ;-)
-        self.assertEqual(instance.unknown, ANSWER_TO_ULTIMATE_QUESTION)
-
-        # We are paranoiac !
-        self.assertEqual(getattr(instance, 'unknown'), ANSWER_TO_ULTIMATE_QUESTION)
+        with self.assertRaises(AttributeError):
+            instance.unknown = 42
diff --git a/odoo/models.py b/odoo/models.py
index 43f477fb1c2..15758441afa 100644
--- a/odoo/models.py
+++ b/odoo/models.py
@@ -53,7 +53,7 @@ from . import api
 from . import tools
 from .exceptions import AccessError, MissingError, ValidationError, UserError
 from .osv.query import Query
-from .tools import frozendict, lazy_classproperty, lazy_property, ormcache, \
+from .tools import frozendict, lazy_classproperty, ormcache, \
                    Collector, LastOrderedSet, OrderedSet, IterableGenerator, \
                    groupby, unique
 from .tools.config import config
@@ -151,6 +151,10 @@ class MetaModel(api.Meta):
 
     module_to_models = defaultdict(list)
 
+    def __new__(meta, name, bases, attrs):
+        attrs.setdefault('__slots__', ())
+        return super().__new__(meta, name, bases, attrs)
+
     def __init__(self, name, bases, attrs):
         if not self._register:
             self._register = True
@@ -253,6 +257,7 @@ class BaseModel(MetaModel('DummyModel', (object,), {'_register': False})):
     To create a class that should not be instantiated,
     the :attr:`~odoo.models.BaseModel._register` attribute may be set to False.
     """
+    __slots__ = ['env', '_ids', '_prefetch_ids']
 
     _auto = False
     """Whether a database table should be created (default: ``True``).
@@ -5607,7 +5612,7 @@ Record ids: %(records)s
     # Cache and recomputation management
     #
 
-    @lazy_property
+    @property
     def _cache(self):
         """ Return the cache of ``self``, mapping field names to values. """
         return RecordCache(self)
@@ -6226,6 +6231,8 @@ collections.Sequence.register(BaseModel)
 
 class RecordCache(MutableMapping):
     """ A mapping from field names to values, to read and update the cache of a record. """
+    __slots__ = ['_record']
+
     def __init__(self, record):
         assert len(record) == 1, "Unexpected RecordCache(%s)" % record
         self._record = record