65 lines
2.4 KiB
ReStructuredText
65 lines
2.4 KiB
ReStructuredText
Callable providers
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------------------
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.. currentmodule:: dependency_injector.providers
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:py:class:`Callable` provider is a provider that wraps particular callable with
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some injections. Every call of this provider returns result of call of initial
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callable.
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Callable providers and injections
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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:py:class:`Callable` takes a various number of positional and keyword
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arguments that are used as decorated callable injections. Every time, when
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:py:class:`Callable` is called, positional and keyword argument injections
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would be passed as an callable arguments.
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Such behaviour is very similar to the standard Python ``functools.partial``
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object, except of one thing: all injectable values are provided
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*"as is"*, except of providers (subclasses of :py:class:`Provider`). Providers
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will be called every time, when injection needs to be done. For example,
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if injectable value of injection is a :py:class:`Factory`, it will provide
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new one instance (as a result of its call) every time, when injection needs
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to be done.
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:py:class:`Callable` behaviour with context positional and keyword arguments
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is very like a standard Python ``functools.partial``:
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- Positional context arguments will be appended after :py:class:`Callable`
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positional injections.
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- Keyword context arguments have priority on :py:class:`Callable` keyword
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injections and will be merged over them.
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Example that shows usage of :py:class:`Callable` with positional argument
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injections:
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.. literalinclude:: ../../examples/providers/callable_args.py
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:language: python
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Next one example shows usage of :py:class:`Callable` with keyword argument
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injections:
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.. image:: /images/providers/callable.png
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:width: 100%
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:align: center
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.. literalinclude:: ../../examples/providers/callable_kwargs.py
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:language: python
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Callable providers delegation
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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:py:class:`Callable` provider could be delegated to any other provider via any
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kind of injection. Delegation of :py:class:`Callable` providers is the same as
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:py:class:`Factory` and :py:class:`Singleton` providers delegation, please
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follow *Factory providers delegation* section for example.
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:py:class:`Callable` delegate could be created obviously using
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``Delegate(Callable(...))`` or by calling ``Callable(...).delegate()`` method.
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Example:
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.. literalinclude:: ../../examples/providers/callable_delegation.py
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:language: python
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