Add simplified syntax for @inject decorator

dependency_injector/injections.py

@@ -1,6 +1,6 @@
 """Injections module."""
 
-from six import wraps
+import six
 
 from .utils import is_provider
 from .utils import ensure_is_injection
@@ -48,28 +48,32 @@ class Method(Injection):
     __IS_METHOD_INJECTION__ = True
 
 
-def inject(injection):
+def inject(*args, **kwargs):
     """Dependency injection decorator.
 
     :type injection: Injection
     :return: (callable) -> (callable)
     """
-    injection = ensure_is_injection(injection)
+    injections = tuple((KwArg(name, value)
+                        for name, value in six.iteritems(kwargs)))
+    if args:
+        injections += tuple((ensure_is_injection(injection)
+                             for injection in args))
 
     def decorator(callback):
         """Dependency injection decorator."""
         if hasattr(callback, '_injections'):
-            callback._injections += (injection,)
+            callback._injections += injections
+            return callback
 
-        @wraps(callback)
+        @six.wraps(callback)
         def decorated(*args, **kwargs):
             """Decorated with dependency injection callback."""
             return callback(*args,
                             **get_injectable_kwargs(kwargs,
-                                                    getattr(decorated,
-                                                            '_injections')))
+                                                    decorated._injections))
 
-        setattr(decorated, '_injections', (injection,))
+        decorated._injections = injections
 
         return decorated
     return decorator

examples/concept.py

@@ -1,15 +1,7 @@
 """Concept example of `Dependency Injector`."""
 
-from dependency_injector.catalog import AbstractCatalog
-
-from dependency_injector.providers import Factory
-from dependency_injector.providers import Singleton
-
-from dependency_injector.injections import KwArg
-from dependency_injector.injections import Attribute
-from dependency_injector.injections import inject
-
 import sqlite3
+import dependency_injector as di
 
 
 class ObjectA(object):
@@ -31,23 +23,23 @@ class ObjectB(object):
         self.db = db
 
 
-class Catalog(AbstractCatalog):
+class Catalog(di.AbstractCatalog):
 
-    """Catalog of dependency_injector providers."""
+    """Catalog of providers."""
 
-    database = Singleton(sqlite3.Connection,
-                         KwArg('database', ':memory:'),
-                         Attribute('row_factory', sqlite3.Row))
-    """:type: (dependency_injector.Provider) -> sqlite3.Connection"""
+    database = di.Singleton(sqlite3.Connection,
+                            di.KwArg('database', ':memory:'),
+                            di.Attribute('row_factory', sqlite3.Row))
+    """:type: (di.Provider) -> sqlite3.Connection"""
 
-    object_a_factory = Factory(ObjectA,
-                               KwArg('db', database))
-    """:type: (dependency_injector.Provider) -> ObjectA"""
+    object_a_factory = di.Factory(ObjectA,
+                                  di.KwArg('db', database))
+    """:type: (di.Provider) -> ObjectA"""
 
-    object_b_factory = Factory(ObjectB,
-                               KwArg('a', object_a_factory),
-                               KwArg('db', database))
-    """:type: (dependency_injector.Provider) -> ObjectB"""
+    object_b_factory = di.Factory(ObjectB,
+                                  di.KwArg('a', object_a_factory),
+                                  di.KwArg('db', database))
+    """:type: (di.Provider) -> ObjectB"""
 
 
 # Catalog static provides.
@@ -60,9 +52,9 @@ assert a1.db is a2.db is b1.db is b2.db is Catalog.database()
 
 
 # Example of inline injections.
-@inject(KwArg('a', Catalog.object_a_factory))
-@inject(KwArg('b', Catalog.object_b_factory))
-@inject(KwArg('database', Catalog.database))
+@di.inject(a=Catalog.object_a_factory)
+@di.inject(b=Catalog.object_b_factory)
+@di.inject(database=Catalog.database)
 def example(a, b, database):
     """Example callback."""
     assert a.db is b.db is database is Catalog.database()

tests/test_injections.py

@@ -76,8 +76,8 @@ class InjectTests(unittest.TestCase):
         provider1 = Factory(object)
         provider2 = Factory(list)
 
-        @inject(KwArg('a', provider1))
-        @inject(KwArg('b', provider2))
+        @inject(a=provider1)
+        @inject(b=provider2)
         def test(a, b):
             return a, b
 
@@ -98,8 +98,8 @@ class InjectTests(unittest.TestCase):
         provider2 = Factory(list)
         object_a = object()
 
-        @inject(KwArg('a', provider1))
-        @inject(KwArg('b', provider2))
+        @inject(a=provider1)
+        @inject(b=provider2)
         def test(a, b):
             return a, b
 
@@ -120,6 +120,27 @@ class InjectTests(unittest.TestCase):
         provider = Factory(list)
         object_a = object()
 
+        @inject(b=provider)
+        def test(a, b):
+            return a, b
+
+        a1, b1 = test(object_a)
+        a2, b2 = test(object_a)
+
+        self.assertIsInstance(a1, object)
+        self.assertIsInstance(a2, object)
+        self.assertIs(a1, object_a)
+        self.assertIs(a2, object_a)
+
+        self.assertIsInstance(b1, list)
+        self.assertIsInstance(b2, list)
+        self.assertIsNot(b1, b2)
+
+    def test_injection_kwarg_syntax(self):
+        """Test `inject()` decorated callback with "old" style using KwArg."""
+        provider = Factory(list)
+        object_a = object()
+
         @inject(KwArg('b', provider))
         def test(a, b):
             return a, b