creating package structure

README.md

@@ -2,3 +2,63 @@ Objects
 =======
 
 Python catalogs of objects providers.
+
+
+Example:
+
+```python
+import objects
+import sqlite3
+
+
+class A(object):
+    def __init__(self, db):
+        self.db = db
+
+
+class B(object):
+    def __init__(self, a, db):
+        self.a = a
+        self.db = db
+
+
+class Catalog(objects.Catalog):
+    """
+    Objects catalog.
+    """
+
+    database = objects.Singleton(sqlite3.Connection,
+                                 database='example.db')
+    """ :type: (objects.Provider) -> sqlite3.Connection """
+
+    object_a = objects.NewInstance(A,
+                                   db=database)
+    """ :type: (objects.Provider) -> A """
+
+    object_b = objects.NewInstance(B,
+                                   a=object_a,
+                                   db=database)
+    """ :type: (objects.Provider) -> B """
+
+
+class Consumer(object):
+    catalog = Catalog(Catalog.object_a,
+                      Catalog.object_b)
+
+    def return_a_b(self):
+        return (self.catalog.object_a(),
+                self.catalog.object_b())
+
+a1, b1 = Consumer().return_a_b()
+
+a2 = Catalog.object_a()
+b2 = Catalog.object_b()
+
+print a1, a1.db
+print a2, a2.db
+print b1, b1.db
+print b2, b2.db
+
+assert a1 is not a2
+assert b1 is not b2
+```

examples/concept.py

@@ -36,10 +36,15 @@ class Catalog(objects.Catalog):
     """ :type: (objects.Provider) -> B """
 
 
-catalog = Catalog(Catalog.object_a,
-                  Catalog.object_b)
-a1 = catalog.object_a()
-b1 = catalog.object_b()
+class Consumer(object):
+    catalog = Catalog(Catalog.object_a,
+                      Catalog.object_b)
+
+    def return_a_b(self):
+        return (self.catalog.object_a(),
+                self.catalog.object_b())
+
+a1, b1 = Consumer().return_a_b()
 
 a2 = Catalog.object_a()
 b2 = Catalog.object_b()

objects/__init__.py

@@ -2,48 +2,10 @@
 `Objects` library.
 """
 
-
-class Catalog(object):
-    def __init__(self, *args):
-        args = set(args)
-        for attribute_name in set(dir(self.__class__)) - set(dir(Catalog)):
-            provider = getattr(self, attribute_name)
-            if not isinstance(provider, Provider):
-                continue
-            if provider not in args:
-                setattr(self, attribute_name, None)
+from .catalog import Catalog
+from .std_providers import (Provider, NewInstance, Singleton, Class, Object,
+                            Function, Value)
 
 
-class Provider(object):
-    def __call__(self, *args, **kwargs):
-        raise NotImplementedError()
-
-
-class NewInstance(Provider):
-    def __init__(self, provides, **dependencies):
-        self.provides = provides
-        self.dependencies = dependencies
-
-    def __call__(self, *args, **kwargs):
-        for name, dependency in self.dependencies.iteritems():
-            if name in kwargs:
-                continue
-
-            if isinstance(dependency, Provider):
-                value = dependency.__call__()
-            else:
-                value = dependency
-
-            kwargs[name] = value
-        return self.provides(*args, **kwargs)
-
-
-class Singleton(NewInstance):
-    def __init__(self, *args, **kwargs):
-        self.instance = None
-        super(Singleton, self).__init__(*args, **kwargs)
-
-    def __call__(self, *args, **kwargs):
-        if not self.instance:
-            self.instance = super(Singleton, self).__call__(*args, **kwargs)
-        return self.instance
+__all__ = ['Catalog', 'Provider', 'NewInstance', 'Singleton', 'Class',
+           'Object', 'Function', 'Value']

objects/catalog.py

@@ -0,0 +1,32 @@
+"""
+Catalog module.
+"""
+
+from .std_providers import Provider
+
+
+class Catalog(object):
+    """
+    Object provides catalog.
+    """
+
+    def __init__(self, *used_providers):
+        """
+        Initializer.
+        """
+        self._clean_unused_providers(used_providers)
+
+    def _clean_unused_providers(self, used_providers):
+        """
+        Sets every catalog's provider in None except of `used_providers` list.
+
+        :param list|tuple|set used_providers:
+        :return:
+        """
+        used_providers = set(used_providers)
+        for attribute_name in set(dir(self.__class__)) - set(dir(Catalog)):
+            provider = getattr(self, attribute_name)
+            if not isinstance(provider, Provider):
+                continue
+            if provider not in used_providers:
+                setattr(self, attribute_name, None)

objects/std_providers.py

@@ -0,0 +1,108 @@
+"""
+Standard providers.
+"""
+
+
+class Provider(object):
+    """
+    Base provider class.
+    """
+
+    def __call__(self, *args, **kwargs):
+        """
+        Returns provided instance.
+        """
+        raise NotImplementedError()
+
+
+class NewInstance(Provider):
+    """
+    New instance providers will create and return new instance on every call.
+    """
+
+    def __init__(self, provides, **dependencies):
+        """
+        Initializer.
+        """
+        self.provides = provides
+        self.dependencies = dependencies
+
+    def __call__(self, *args, **kwargs):
+        """
+        Returns provided instance.
+        """
+        for name, dependency in self.dependencies.iteritems():
+            if name in kwargs:
+                continue
+
+            if isinstance(dependency, Provider):
+                value = dependency.__call__()
+            else:
+                value = dependency
+
+            kwargs[name] = value
+        return self.provides(*args, **kwargs)
+
+
+class Singleton(NewInstance):
+    """
+    Singleton provider will create instance once and return it on every call.
+    """
+
+    def __init__(self, *args, **kwargs):
+        """
+        Initializer.
+        """
+        self.instance = None
+        super(Singleton, self).__init__(*args, **kwargs)
+
+    def __call__(self, *args, **kwargs):
+        """
+        Returns provided instance.
+        """
+        if not self.instance:
+            self.instance = super(Singleton, self).__call__(*args, **kwargs)
+        return self.instance
+
+
+class _StaticProvider(Provider):
+    """
+    Static provider is base implementation that provides exactly the same as
+    it got on input.
+    """
+
+    def __init__(self, provides):
+        """
+        Initializer.
+        """
+        self.provides = provides
+
+    def __call__(self):
+        """
+        Returns provided instance.
+        """
+        return self.provides
+
+
+class Class(_StaticProvider):
+    """
+    Class provider provides class.
+    """
+
+
+class Object(_StaticProvider):
+    """
+    Object provider provides object.
+    """
+
+
+class Function(_StaticProvider):
+    """
+    Function provider provides function.
+    """
+
+
+class Value(_StaticProvider):
+    """
+    Value provider provides value.
+    """