Merge pull request ivankorobkov#6 from panki/master

Parameter injection, fixed ivankorobkov#3.

Author: ivankorobkov

src/inject.py

@@ -76,6 +76,7 @@ def my_config(binder):
 
 import logging
 import threading
+from functools import wraps
 
 logger = logging.getLogger('inject')
 
@@ -126,6 +127,11 @@ def attr(cls):
     return _AttributeInjection(cls)
 
 
+def param(name, cls=None):
+    """Return a parameter injection decorator"""
+    return _ParameterInjection(name, cls)
+
+
 def get_injector():
     """Return the current injector or None."""
     return _INJECTOR
@@ -246,3 +252,19 @@ def __init__(self, cls):
 
     def __get__(self, obj, owner):
         return instance(self._cls)
+
+
+class _ParameterInjection(object):
+    __slots__ = ('_name', '_cls')
+
+    def __init__(self, name, cls=None):
+        self._name = name
+        self._cls = cls
+
+    def __call__(self, func):
+        @wraps(func)
+        def injection_wrapper(*args, **kwargs):
+            if not self._name in kwargs:
+                kwargs[self._name] = instance(self._cls or self._name)
+            return func(*args, **kwargs)
+        return injection_wrapper

src/test_inject.py

@@ -146,6 +146,26 @@ class MyClass(object):
         assert value0 == 123
         assert value1 == 123
 
+    def test_param_by_name(self):
+        @inject.param('val')
+        def test_func(val=None):
+            return val
+
+        inject.configure(lambda binder: binder.bind('val', 123))
+
+        assert test_func() == 123
+        assert test_func(val=321) == 321
+
+    def test_param_by_class(self):
+        @inject.param('val', int)
+        def test_func(val):
+            return val
+
+        inject.configure(lambda binder: binder.bind(int, 123))
+
+        assert test_func() == 123
+
+
 
 class TestFunctional(TestCase):
     def tearDown(self):