Add simplified kwarg injections syntax for Factory and Singleton providers

dependency_injector/providers.py

@@ -1,6 +1,8 @@
 """Providers module."""
 
-from six import class_types
+import six
+
+from .injections import KwArg
 
 from .utils import ensure_is_provider
 from .utils import is_kwarg_injection
@@ -100,7 +102,7 @@ class Factory(Provider):
 
     __slots__ = ('_provides', '_kwargs', '_attributes', '_methods')
 
-    def __init__(self, provides, *injections):
+    def __init__(self, provides, *injections, **kwargs):
         """Initializer."""
         if not callable(provides):
             raise Error('Factory provider expects to get callable, ' +
@@ -109,6 +111,9 @@ class Factory(Provider):
         self._kwargs = tuple((injection
                               for injection in injections
                               if is_kwarg_injection(injection)))
+        if kwargs:
+            self._kwargs += tuple((KwArg(name, value)
+                                  for name, value in six.iteritems(kwargs)))
         self._attributes = tuple((injection
                                   for injection in injections
                                   if is_attribute_injection(injection)))
@@ -149,10 +154,10 @@ class Singleton(Provider):
 
     __slots__ = ('_instance', '_factory')
 
-    def __init__(self, provides, *injections):
+    def __init__(self, provides, *injections, **kwargs):
         """Initializer."""
         self._instance = None
-        self._factory = Factory(provides, *injections)
+        self._factory = Factory(provides, *injections, **kwargs)
         super(Singleton, self).__init__()
 
     def _provide(self, *args, **kwargs):
@@ -178,7 +183,7 @@ class ExternalDependency(Provider):
 
     def __init__(self, instance_of):
         """Initializer."""
-        if not isinstance(instance_of, class_types):
+        if not isinstance(instance_of, six.class_types):
             raise Error('ExternalDependency provider expects to get class, ' +
                         'got {0} instead'.format(str(instance_of)))
         self._instance_of = instance_of

examples/concept.py

@@ -28,17 +28,16 @@ class Catalog(di.AbstractCatalog):
     """Catalog of providers."""
 
     database = di.Singleton(sqlite3.Connection,
-                            di.KwArg('database', ':memory:'),
+                            database=':memory:')
-                            di.Attribute('row_factory', sqlite3.Row))
     """:type: (di.Provider) -> sqlite3.Connection"""
 
     object_a_factory = di.Factory(ObjectA,
-                                  di.KwArg('db', database))
+                                  db=database)
     """:type: (di.Provider) -> ObjectA"""
 
     object_b_factory = di.Factory(ObjectB,
-                                  di.KwArg('a', object_a_factory),
+                                  a=object_a_factory,
-                                  di.KwArg('db', database))
+                                  db=database)
     """:type: (di.Provider) -> ObjectB"""
 
 

tests/test_providers.py

@@ -223,6 +223,28 @@ class FactoryTests(unittest.TestCase):
         self.assertIsInstance(instance1, self.Example)
         self.assertIsInstance(instance2, self.Example)
 
+    def test_call_with_init_args_simplified_syntax(self):
+        """Test creation of new instances with init args injections.
+
+        Simplified syntax.
+        """
+        provider = Factory(self.Example,
+                           init_arg1='i1',
+                           init_arg2='i2')
+
+        instance1 = provider()
+        instance2 = provider()
+
+        self.assertEqual(instance1.init_arg1, 'i1')
+        self.assertEqual(instance1.init_arg2, 'i2')
+
+        self.assertEqual(instance2.init_arg1, 'i1')
+        self.assertEqual(instance2.init_arg2, 'i2')
+
+        self.assertIsNot(instance1, instance2)
+        self.assertIsInstance(instance1, self.Example)
+        self.assertIsInstance(instance2, self.Example)
+
     def test_call_with_attributes(self):
         """Test creation of new instances with attribute injections."""
         provider = Factory(self.Example,