Adding config provider

README.md

@@ -132,6 +132,7 @@ class ObjectA(object):
         self.db = db
 
 
+# Mock of example class.
 class ObjectAMock(ObjectA):
     pass
 
@@ -357,3 +358,74 @@ assert arg1 == 1
 assert arg2 == 2
 assert arg3 == 3
 ```
+
+Example of objects catalog with config provider:
+
+```python
+"""
+Config provider examples.
+"""
+
+from objects import AbstractCatalog
+from objects.providers import Config, NewInstance
+from objects.injections import InitArg
+
+
+# Some example class.
+class ObjectA(object):
+    def __init__(self, setting_one, setting_two, setting_three):
+        self.setting_one = setting_one
+        self.setting_two = setting_two
+        self.setting_three = setting_three
+
+
+# Catalog of objects providers.
+class Catalog(AbstractCatalog):
+    """
+    Objects catalog.
+    """
+
+    config = Config()
+    """ :type: (objects.Config) """
+
+    object_a = NewInstance(ObjectA,
+                           InitArg('setting_one', config.SETTING_ONE),
+                           InitArg('setting_two', config.SETTING_TWO),
+                           InitArg('setting_three', config.GLOBAL.SETTING_THREE))
+    """ :type: (objects.Provider) -> ObjectA """
+
+
+# Setting config value and making some tests.
+Catalog.config.update_from({
+    'SETTING_ONE': 1,
+    'SETTING_TWO': 2,
+    'GLOBAL': {
+        'SETTING_THREE': 3
+    }
+})
+
+object_a1 = Catalog.object_a()
+
+assert object_a1.setting_one == 1
+assert object_a1.setting_two == 2
+assert object_a1.setting_three == 3
+
+# Changing config value one more time and making some tests.
+Catalog.config.update_from({
+    'SETTING_ONE': 11,
+    'SETTING_TWO': 22,
+    'GLOBAL': {
+        'SETTING_THREE': 33
+    }
+})
+
+object_a2 = Catalog.object_a()
+
+assert object_a2.setting_one == 11
+assert object_a2.setting_two == 22
+assert object_a2.setting_three == 33
+
+assert object_a1.setting_one == 1
+assert object_a1.setting_two == 2
+assert object_a1.setting_three == 3
+```

examples/config_provider.py

@@ -0,0 +1,66 @@
+"""
+Config provider examples.
+"""
+
+from objects import AbstractCatalog
+from objects.providers import Config, NewInstance
+from objects.injections import InitArg
+
+
+# Some example class.
+class ObjectA(object):
+    def __init__(self, setting_one, setting_two, setting_three):
+        self.setting_one = setting_one
+        self.setting_two = setting_two
+        self.setting_three = setting_three
+
+
+# Catalog of objects providers.
+class Catalog(AbstractCatalog):
+    """
+    Objects catalog.
+    """
+
+    config = Config()
+    """ :type: (objects.Config) """
+
+    object_a = NewInstance(ObjectA,
+                           InitArg('setting_one', config.SETTING_ONE),
+                           InitArg('setting_two', config.SETTING_TWO),
+                           InitArg('setting_three', config.GLOBAL.SETTING_THREE))
+    """ :type: (objects.Provider) -> ObjectA """
+
+
+# Setting config value and making some tests.
+Catalog.config.update_from({
+    'SETTING_ONE': 1,
+    'SETTING_TWO': 2,
+    'GLOBAL': {
+        'SETTING_THREE': 3
+    }
+})
+
+object_a1 = Catalog.object_a()
+
+assert object_a1.setting_one == 1
+assert object_a1.setting_two == 2
+assert object_a1.setting_three == 3
+
+# Changing config value one more time and making some tests.
+Catalog.config.update_from({
+    'SETTING_ONE': 11,
+    'SETTING_TWO': 22,
+    'GLOBAL': {
+        'SETTING_THREE': 33
+    }
+})
+
+object_a2 = Catalog.object_a()
+
+assert object_a2.setting_one == 11
+assert object_a2.setting_two == 22
+assert object_a2.setting_three == 33
+
+assert object_a1.setting_one == 1
+assert object_a1.setting_two == 2
+assert object_a1.setting_three == 3

examples/overrides.py

@@ -16,6 +16,7 @@ class ObjectA(object):
         self.db = db
 
 
+# Mock of example class.
 class ObjectAMock(ObjectA):
     pass
 

objects/providers.py

@@ -251,7 +251,7 @@ class Value(_StaticProvider):
 
 class Callable(Provider):
     """
-    Callable providers will provides callable calls with some predefined
+    Callable provider will provide callable calls with some predefined
     dependencies injections.
     """
 
@@ -275,3 +275,68 @@ class Callable(Provider):
         injections.update(kwargs)
 
         return self.calls(*args, **injections)
+
+
+class _DeferredConfig(Provider):
+    """
+    Deferred config providers provide an value from the root config object.
+    """
+    def __init__(self, paths, root_config):
+        """
+        Initializer.
+        """
+        self.paths = paths
+        self.root_config = root_config
+        super(_DeferredConfig, self).__init__()
+
+    def __getattr__(self, item):
+        """
+        Returns instance of deferred config.
+        """
+        return _DeferredConfig(paths=self.paths + (item,),
+                               root_config=self.root_config)
+
+    def __call__(self, *args, **kwargs):
+        """
+        Returns provided instance.
+        """
+        return self.root_config(self.paths)
+
+
+class Config(Provider):
+    """
+    Config provider provides dict values. Also config provider creates
+    deferred config objects for all undefined attribute calls.
+    """
+
+    def __init__(self, value=None):
+        """
+        Initializer.
+        """
+        if not value:
+            value = dict()
+        self.value = value
+        super(Config, self).__init__()
+
+    def update_from(self, value):
+        """
+        Updates current value from another one.
+        """
+        self.value.update(value)
+
+    def __getattr__(self, item):
+        """
+        Returns instance of deferred config.
+        """
+        return _DeferredConfig(paths=(item,),
+                               root_config=self)
+
+    def __call__(self, paths=None):
+        """
+        Returns provided instance.
+        """
+        value = self.value
+        if paths:
+            for path in paths:
+                value = value[path]
+        return value