Remove the creation counter for Property. Fixes #6317. (googleapis#6335)

MIGRATION_NOTES.md

@@ -56,8 +56,10 @@ The primary differences come from:
   original implementation didn't allow in excess of 500 bytes, but it seems
   the limit has been raised by the backend. (FWIW, Danny's opinion is that
   the backend should enforce these limits, not the library.)
-- I renamed `Property.__creation_counter_global` to
-  `Property._CREATION_COUNTER`.
+- `Property.__creation_counter_global` has been removed as it seems to have
+  been included for a feature that was never implemented. See 
+  [Issue #175][1] for original rationale for including it and [Issue #6317][2]
+  for discussion of its removal.
 - `ndb` uses "private" instance attributes in many places, e.g. `Key.__app`.
   The current implementation (for now) just uses "protected" attribute names,
   e.g. `Key._key` (the implementation has changed in the rewrite). We may want
@@ -125,11 +127,13 @@ The primary differences come from:
 - The whole `bytes` vs. `str` issue needs to be considered package-wide.
   For example, the `Property()` constructor always encoded Python 2 `unicode`
   to a Python 2 `str` (i.e. `bytes`) with the `utf-8` encoding. This fits
-  in some sense: the property name in the [protobuf definition][1] is a
+  in some sense: the property name in the [protobuf definition][3] is a
   `string` (i.e. UTF-8 encoded text). However, there is a bit of a disconnect
   with other types that use property names, e.g. `FilterNode`.
 - There is a giant web of module interdependency, so runtime imports (to avoid
   import cycles) are very common. For example `model.Property` depends on
   `query` but `query` depends on `model`.
 
-[1]: https://github.com/googleapis/googleapis/blob/3afba2fd062df0c89ecd62d97f912192b8e0e0ae/google/datastore/v1/entity.proto#L203
+[1]: https://github.com/GoogleCloudPlatform/datastore-ndb-python/issues/175
+[2]: https://github.com/googleapis/google-cloud-python/issues/6317
+[3]: https://github.com/googleapis/googleapis/blob/3afba2fd062df0c89ecd62d97f912192b8e0e0ae/google/datastore/v1/entity.proto#L203

src/google/cloud/ndb/model.py

@@ -348,7 +348,6 @@ class Property(ModelAttribute):
     _verbose_name = None
     _write_empty_list = False
     # Non-public class attributes.
-    _CREATION_COUNTER = 0
     _FIND_METHODS_CACHE = {}
 
     def __init__(
@@ -385,9 +384,6 @@ def __init__(
             self._verbose_name = verbose_name
         if write_empty_list is not None:
             self._write_empty_list = write_empty_list
-        # Keep a unique creation counter. Note that this is not threadsafe.
-        Property._CREATION_COUNTER += 1
-        self._creation_counter = Property._CREATION_COUNTER
 
     @staticmethod
     def _verify_name(name):

tests/unit/test_model.py

@@ -330,25 +330,12 @@ def test___hash__():
             hash(wrapped)
 
 
-@pytest.fixture
-def zero_prop_counter():
-    counter_val = model.Property._CREATION_COUNTER
-    model.Property._CREATION_COUNTER = 0
-    try:
-        yield
-    finally:
-        model.Property._CREATION_COUNTER = counter_val
-
-
 class TestProperty:
     @staticmethod
-    def test_constructor_defaults(zero_prop_counter):
+    def test_constructor_defaults():
         prop = model.Property()
-        # Check that the creation counter was updated.
-        assert model.Property._CREATION_COUNTER == 1
-        assert prop._creation_counter == 1
         # Check that none of the constructor defaults were used.
-        assert prop.__dict__ == {"_creation_counter": 1}
+        assert prop.__dict__ == {}
 
     @staticmethod
     def _example_validator(prop, value):
@@ -360,7 +347,7 @@ def test__example_validator(self):
         assert validated == "abcde"
         assert self._example_validator(None, validated) == "abcde"
 
-    def test_constructor_explicit(self, zero_prop_counter):
+    def test_constructor_explicit(self):
         prop = model.Property(
             name="val",
             indexed=False,
@@ -381,43 +368,32 @@ def test_constructor_explicit(self, zero_prop_counter):
         assert prop._validator is self._example_validator
         assert prop._verbose_name == "VALUE FOR READING"
         assert not prop._write_empty_list
-        # Check that the creation counter was updated.
-        assert model.Property._CREATION_COUNTER == 1
-        assert prop._creation_counter == 1
 
     @staticmethod
-    def test_constructor_invalid_name(zero_prop_counter):
+    def test_constructor_invalid_name():
         with pytest.raises(TypeError):
             model.Property(name=["not", "a", "string"])
         with pytest.raises(ValueError):
             model.Property(name="has.a.dot")
-        # Check that the creation counter was not updated.
-        assert model.Property._CREATION_COUNTER == 0
 
     @staticmethod
-    def test_constructor_repeated_not_allowed(zero_prop_counter):
+    def test_constructor_repeated_not_allowed():
         with pytest.raises(ValueError):
             model.Property(name="a", repeated=True, required=True)
         with pytest.raises(ValueError):
             model.Property(name="b", repeated=True, default="zim")
-        # Check that the creation counter was not updated.
-        assert model.Property._CREATION_COUNTER == 0
 
     @staticmethod
-    def test_constructor_invalid_choices(zero_prop_counter):
+    def test_constructor_invalid_choices():
         with pytest.raises(TypeError):
             model.Property(name="a", choices={"wrong": "container"})
-        # Check that the creation counter was not updated.
-        assert model.Property._CREATION_COUNTER == 0
 
     @staticmethod
-    def test_constructor_invalid_validator(zero_prop_counter):
+    def test_constructor_invalid_validator():
         with pytest.raises(TypeError):
             model.Property(
                 name="a", validator=unittest.mock.sentinel.validator
             )
-        # Check that the creation counter was not updated.
-        assert model.Property._CREATION_COUNTER == 0
 
     def test_repr(self):
         prop = model.Property(