python-dependency-injector/docs/providers/callable.rst
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Callable providers
------------------
.. currentmodule:: dependency_injector.providers
:py:class:`Callable` provider calls wrapped callable on every call.
Callable providers and injections
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
:py:class:`Callable` provider takes a various number of positional and keyword
arguments that are used as wrapped callable injections. Every time, when
:py:class:`Callable` provider is called, positional and keyword argument
injections would be passed as callable arguments.
Injections are done according to the next rules:
+ All providers (instances of :py:class:`Provider`) are called every time
when injection needs to be done.
+ Providers could be injected "as is" (delegated), if it is defined obviously.
Check out :ref:`callable_providers_delegation`.
+ All other injectable values are provided *"as is"*.
+ Positional context arguments will be appended after :py:class:`Callable`
positional injections.
+ Keyword context arguments have priority on :py:class:`Callable` keyword
injections and will be merged over them.
Example that shows usage of :py:class:`Callable` with positional argument
injections:
.. literalinclude:: ../../examples/providers/callable_args.py
:language: python
Next one example shows usage of :py:class:`Callable` with keyword argument
injections:
.. image:: /images/providers/callable.png
:width: 100%
:align: center
.. literalinclude:: ../../examples/providers/callable_kwargs.py
:language: python
.. _callable_providers_delegation:
Callable providers delegation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
:py:class:`Callable` provider could be delegated to any other provider via
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
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::