Improve functionality of catalog overriding

dependency_injector/catalog.py

@@ -87,6 +87,8 @@ class CatalogMetaClass(type):
         cls.inherited_providers = inherited_providers
         cls.providers = providers
 
+        cls.overridden_by = tuple()
+
         cls.Bundle = mcs.bundle_cls_factory(cls)
 
         for name, provider in six.iteritems(cls_providers):
@@ -104,6 +106,19 @@ class CatalogMetaClass(type):
         """Create bundle class for catalog."""
         return type('{0}Bundle', (CatalogBundle,), dict(catalog=cls))
 
+    @property
+    def is_overridden(cls):
+        """Check if catalog is overridden by another catalog."""
+        return bool(cls.overridden_by)
+
+    @property
+    def last_overriding(cls):
+        """Return last overriding catalog."""
+        try:
+            return cls.overridden_by[-1]
+        except (TypeError, IndexError):
+            raise Error('Catalog {0} is not overridden'.format(str(cls)))
+
     def __repr__(cls):
         """Return string representation of the catalog class."""
         return '<Catalog "' + '.'.join((cls.__module__, cls.__name__)) + '">'
@@ -113,6 +128,9 @@ class CatalogMetaClass(type):
 class AbstractCatalog(object):
     """Abstract providers catalog.
 
+    :type Bundle: CatalogBundle
+    :param Bundle: Catalog's bundle class
+
     :type providers: dict[str, dependency_injector.Provider]
     :param providers: Dict of all catalog providers, including inherited from
         parent catalogs
@@ -124,8 +142,15 @@ class AbstractCatalog(object):
     :param inherited_providers: Dict of providers, that are inherited from
         parent catalogs
 
-    :type Bundle: CatalogBundle
-    :param Bundle: Catalog's bundle class
+    :type overridden_by: tuple[AbstractCatalog]
+    :param overridden_by: Tuple of overriding catalogs
+
+    :type is_overridden: bool
+    :param is_overridden: Read-only, evaluated in runtime, property that is
+        set to True if catalog is overridden
+
+    :type last_overriding: AbstractCatalog | None
+    :param last_overriding: Reference to the last overriding catalog, if any
     """
 
     Bundle = CatalogBundle
@@ -134,6 +159,10 @@ class AbstractCatalog(object):
     inherited_providers = dict()
     providers = dict()
 
+    overridden_by = tuple()
+    is_overridden = bool
+    last_overriding = None
+
     __IS_CATALOG__ = True
 
     @classmethod
@@ -154,9 +183,26 @@ class AbstractCatalog(object):
 
         :type overriding: AbstractCatalog
         """
+        cls.overridden_by += (overriding,)
         for name, provider in six.iteritems(overriding.cls_providers):
             cls.providers[name].override(provider)
 
+    @classmethod
+    def reset_last_overriding(cls):
+        """Reset last overriding catalog."""
+        if not cls.is_overridden:
+            raise Error('Catalog {0} is not overridden'.format(str(cls)))
+        cls.overridden_by = cls.overridden_by[:-1]
+        for provider in six.itervalues(cls.providers):
+            provider.reset_last_overriding()
+
+    @classmethod
+    def reset_override(cls):
+        """Reset all overridings for all catalog providers."""
+        cls.overridden_by = tuple()
+        for provider in six.itervalues(cls.providers):
+            provider.reset_override()
+
     @classmethod
     def get(cls, name):
         """Return provider with specified name or raises error."""

docs/catalogs/overriding.rst

@@ -20,3 +20,15 @@ Example of overriding catalog using ``@di.override()`` decorator:
 .. literalinclude:: ../../examples/catalogs/override_decorator.py
    :language: python
 
+Also there are several useful methods and properties that help to work with 
+catalog overridings:
+
+- ``di.AbstractCatalog.is_overridden`` - read-only, evaluated in runtime, 
+  property that is set to True if catalog is overridden.
+- ``di.AbstractCatalog.last_overriding`` - reference to the last overriding 
+  catalog, if any.
+- ``di.AbstractCatalog.overridden_by`` - tuple of all overriding catalogs.
+- ``di.AbstractCatalog.reset_last_overriding()`` - reset last overriding 
+  catalog.
+- ``di.AbstractCatalog.reset_override()`` - reset all overridings for all 
+  catalog providers. 

docs/main/changelog.rst

@@ -12,7 +12,8 @@ Development version
 -------------------
 
 - Add functionality for creating ``di.AbstractCatalog`` provider bundles.
-- Enhance ``di.AbstractCatalog`` inheritance.
+- Improve ``di.AbstractCatalog`` inheritance.
+- Improve ``di.AbstractCatalog`` overriding.
 - Add images for catalog "Writing catalogs" and "Operating with catalogs" 
   examples.
 - Add functionality for using positional argument injections with 

tests/test_catalog.py

@@ -198,7 +198,7 @@ class CatalogTests(unittest.TestCase):
 
 
 class OverrideTests(unittest.TestCase):
-    """Override decorator test cases."""
+    """Catalog overriding and override decorator test cases."""
 
     class Catalog(di.AbstractCatalog):
         """Test catalog."""
@@ -206,6 +206,10 @@ class OverrideTests(unittest.TestCase):
         obj = di.Object(object())
         another_obj = di.Object(object())
 
+    def tearDown(self):
+        """Tear test environment down."""
+        self.Catalog.reset_override()
+
     def test_overriding(self):
         """Test catalog overriding with another catalog."""
         @di.override(self.Catalog)
@@ -217,3 +221,77 @@ class OverrideTests(unittest.TestCase):
 
         self.assertEqual(self.Catalog.obj(), 1)
         self.assertEqual(self.Catalog.another_obj(), 2)
+
+    def test_is_overridden(self):
+        """Test catalog is_overridden property."""
+        self.assertFalse(self.Catalog.is_overridden)
+
+        @di.override(self.Catalog)
+        class OverridingCatalog(self.Catalog):
+            """Overriding catalog."""
+
+        self.assertTrue(self.Catalog.is_overridden)
+
+    def test_last_overriding(self):
+        """Test catalog last_overriding property."""
+        @di.override(self.Catalog)
+        class OverridingCatalog1(self.Catalog):
+            """Overriding catalog."""
+
+        @di.override(self.Catalog)
+        class OverridingCatalog2(self.Catalog):
+            """Overriding catalog."""
+
+        self.assertIs(self.Catalog.last_overriding, OverridingCatalog2)
+
+    def test_last_overriding_on_not_overridden(self):
+        """Test catalog last_overriding property on not overridden catalog."""
+        with self.assertRaises(di.Error):
+            self.Catalog.last_overriding
+
+    def test_reset_last_overriding(self):
+        """Test resetting last overriding catalog."""
+        @di.override(self.Catalog)
+        class OverridingCatalog1(self.Catalog):
+            """Overriding catalog."""
+
+            obj = di.Value(1)
+            another_obj = di.Value(2)
+
+        @di.override(self.Catalog)
+        class OverridingCatalog2(self.Catalog):
+            """Overriding catalog."""
+
+            obj = di.Value(3)
+            another_obj = di.Value(4)
+
+        self.Catalog.reset_last_overriding()
+
+        self.assertEqual(self.Catalog.obj(), 1)
+        self.assertEqual(self.Catalog.another_obj(), 2)
+
+    def test_reset_last_overriding_when_not_overridden(self):
+        """Test resetting last overriding catalog when it is not overridden."""
+        with self.assertRaises(di.Error):
+            self.Catalog.reset_last_overriding()
+
+    def test_reset_override(self):
+        """Test resetting all catalog overrides."""
+        @di.override(self.Catalog)
+        class OverridingCatalog1(self.Catalog):
+            """Overriding catalog."""
+
+            obj = di.Value(1)
+            another_obj = di.Value(2)
+
+        @di.override(self.Catalog)
+        class OverridingCatalog2(self.Catalog):
+            """Overriding catalog."""
+
+            obj = di.Value(3)
+            another_obj = di.Value(4)
+
+        self.Catalog.reset_override()
+
+        self.assertIsInstance(self.Catalog.obj(), object)
+        self.assertIsInstance(self.Catalog.another_obj(), object)