From 3786b052a908b0520edf09f1beefc8e9a5e7e164 Mon Sep 17 00:00:00 2001
From: Roman Mogilatov <roman.mogilatov@cupid.com>
Date: Wed, 28 Jan 2015 00:48:33 +0200
Subject: [PATCH] adding callable provider with examples

---
 README.md                     | 47 +++++++++++++++++++++++++++++++++++
 examples/callable_provider.py | 42 +++++++++++++++++++++++++++++++
 objects/providers.py          | 30 +++++++++++++++++++++-
 3 files changed, 118 insertions(+), 1 deletion(-)
 create mode 100644 examples/callable_provider.py

diff --git a/README.md b/README.md
index 293e649e..7e604ec1 100644
--- a/README.md
+++ b/README.md
@@ -310,3 +310,50 @@ assert (object_a2 is not object_a3) and \
        (object_a2 is not object_a5) and \
        (object_a2 is not object_a6)
 ```
+
+Example of objects catalog with callable provider:
+
+```python
+"""
+Callable provider examples.
+"""
+
+from objects import AbstractCatalog
+from objects.providers import Singleton, Callable
+from objects.injections import Injection, InitArg, Attribute
+
+import sqlite3
+
+
+# Some example function.
+def consuming_function(arg, db):
+    return arg, db
+
+
+# Catalog of objects providers.
+class Catalog(AbstractCatalog):
+    """
+    Objects catalog.
+    """
+
+    database = Singleton(sqlite3.Connection,
+                         InitArg('database', ':memory:'),
+                         Attribute('row_factory', sqlite3.Row))
+    """ :type: (objects.Provider) -> sqlite3.Connection """
+
+    consuming_function = Callable(consuming_function,
+                                  Injection('db', database))
+    """ :type: (objects.Provider) -> consuming_function """
+
+
+# Some calls.
+arg1, db1 = Catalog.consuming_function(1)
+arg2, db2 = Catalog.consuming_function(2)
+arg3, db3 = Catalog.consuming_function(3)
+
+# Some asserts.
+assert db1 is db2 is db3
+assert arg1 == 1
+assert arg2 == 2
+assert arg3 == 3
+```
diff --git a/examples/callable_provider.py b/examples/callable_provider.py
new file mode 100644
index 00000000..3e037c81
--- /dev/null
+++ b/examples/callable_provider.py
@@ -0,0 +1,42 @@
+"""
+Callable provider examples.
+"""
+
+from objects import AbstractCatalog
+from objects.providers import Singleton, Callable
+from objects.injections import Injection, InitArg, Attribute
+
+import sqlite3
+
+
+# Some example function.
+def consuming_function(arg, db):
+    return arg, db
+
+
+# Catalog of objects providers.
+class Catalog(AbstractCatalog):
+    """
+    Objects catalog.
+    """
+
+    database = Singleton(sqlite3.Connection,
+                         InitArg('database', ':memory:'),
+                         Attribute('row_factory', sqlite3.Row))
+    """ :type: (objects.Provider) -> sqlite3.Connection """
+
+    consuming_function = Callable(consuming_function,
+                                  Injection('db', database))
+    """ :type: (objects.Provider) -> consuming_function """
+
+
+# Some calls.
+arg1, db1 = Catalog.consuming_function(1)
+arg2, db2 = Catalog.consuming_function(2)
+arg3, db3 = Catalog.consuming_function(3)
+
+# Some asserts.
+assert db1 is db2 is db3
+assert arg1 == 1
+assert arg2 == 2
+assert arg3 == 3
diff --git a/objects/providers.py b/objects/providers.py
index 2d0fbdd1..9b0a63dc 100644
--- a/objects/providers.py
+++ b/objects/providers.py
@@ -3,7 +3,7 @@ Standard providers.
 """
 
 from collections import Iterable
-from .injections import InitArg, Attribute, Method
+from .injections import Injection, InitArg, Attribute, Method
 
 
 class Provider(object):
@@ -247,3 +247,31 @@ class Value(_StaticProvider):
     """
     Value provider provides value.
     """
+
+
+class Callable(Provider):
+    """
+    Callable providers will provides callable calls with some predefined
+    dependencies injections.
+    """
+
+    def __init__(self, calls, *injections):
+        """
+        Initializer.
+        """
+        self.calls = calls
+        self.injections = fetch_injections(injections, Injection)
+        super(Callable, self).__init__()
+
+    def __call__(self, *args, **kwargs):
+        """
+        Returns provided instance.
+        """
+        if self.__overridden_by__:
+            return self.__overridden_by__[-1].__call__(*args, **kwargs)
+
+        injections = prepare_injections(self.injections)
+        injections = dict(injections)
+        injections.update(kwargs)
+
+        return self.calls(*args, **injections)