Add docs for abstract callable and singleton providers

docs/providers/callable.rst

@@ -54,8 +54,18 @@ any kind of injection.
 Delegation of :py:class:`Callable` providers is the same as 
 :py:class:`Factory` providers delegation, please follow 
 :ref:`factory_providers_delegation` section for examples (with exception 
-about using :py:class:`DelegatedCallable` instead of 
+of using :py:class:`DelegatedCallable` instead of
 :py:class:`DelegatedFactory`).
 
+Abstract callable providers
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+:py:class:`AbstractCallable` provider is a :py:class:`Callable` provider that
+must be explicitly overridden before calling.
+
+Behaviour of :py:class:`AbstractCallable` providers is the same as of
+:py:class:`AbstractFactory`, please follow :ref:`abstract_factory_providers`
+section for examples (with exception of using :py:class:`AbstractCallable`
+provider instead of :py:class:`AbstractFactory`).
 
 .. disqus::

docs/providers/factory.rst

@@ -106,16 +106,18 @@ provided type:
    :language: python
    :linenos:
 
+.. _abstract_factory_providers:
+
 Abstract factory providers
 ~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-:py:class:`AbstractFactory` is a :py:class:`Factory` provider that must be
+:py:class:`AbstractFactory` provider is a :py:class:`Factory` provider that
-explicitly overridden before calling.
+must be explicitly overridden before calling.
 
 .. note::
 
-    Overriding of :py:class:`AbstractFactory` is possible only by another
+    Overriding of :py:class:`AbstractFactory` provider is possible only by
-    :py:class:`Factory` provider.
+    another :py:class:`Factory` provider.
 
 :py:class:`AbstractFactory` provider is useful when it is needed to specify
 explicitly that it only provides abstraction, but not an implementation.

docs/providers/singleton.rst

@@ -65,7 +65,7 @@ any kind of injection.
 Delegation of :py:class:`Singleton` providers is the same as 
 :py:class:`Factory` providers delegation, please follow 
 :ref:`factory_providers_delegation` section for examples (with exception 
-about using :py:class:`DelegatedSingleton` instead of 
+of using :py:class:`DelegatedSingleton` instead of
 :py:class:`DelegatedFactory`).
 
 Singleton providers specialization
@@ -78,6 +78,17 @@ Specialization of :py:class:`Singleton` providers is the same as
 :py:class:`Factory` providers specialization, please follow 
 :ref:`factory_providers_specialization` section for examples.
 
+Abstract singleton providers
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+:py:class:`AbstractSingleton` provider is a :py:class:`Singleton` provider that
+must be explicitly overridden before calling.
+
+Behaviour of :py:class:`AbstractSingleton` providers is the same as of
+:py:class:`AbstractFactory`, please follow :ref:`abstract_factory_providers`
+section for examples (with exception of using :py:class:`AbstractSingleton`
+provider instead of :py:class:`AbstractFactory`).
+
 Singleton providers and multi-threading
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~