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74 lines
2.3 KiB
ReStructuredText
74 lines
2.3 KiB
ReStructuredText
Callable providers
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------------------
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``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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``Callable`` provider uses ``KwArg`` injections. ``KwArg`` injections are
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done by passing injectable values as keyword arguments during call time.
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Context keyword arguments have higher priority than ``KwArg`` injections.
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Example:
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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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.. code-block:: python
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"""`Callable` providers example."""
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from passlib.hash import sha256_crypt
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from objects.providers import Callable
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from objects.injections import KwArg
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# Password hasher and verifier providers (hash function could be changed
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# anytime (for example, to sha512) without any changes in client's code):
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password_hasher = Callable(sha256_crypt.encrypt,
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KwArg('salt_size', 16),
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KwArg('rounds', 10000))
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password_verifier = Callable(sha256_crypt.verify)
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# Making some asserts (client's code):
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hashed_password = password_hasher('super secret')
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assert password_verifier('super secret', hashed_password)
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Callable providers delegation
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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``Callable`` provider could be delegated to any other provider via any kind of
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injection. Delegation of ``Callable`` providers is the same as ``Factory`` and
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``Singleton`` providers delegation, please follow *Factory providers
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delegation* section for example.
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``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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.. code-block:: python
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"""`Callable` providers delegation example."""
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import sys
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from objects.providers import Callable
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from objects.providers import Delegate
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# Some callable provider and few delegates of it:
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callable_provider = Callable(sys.exit)
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callable_provider_delegate1 = callable_provider.delegate()
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callable_provider_delegate2 = Delegate(callable_provider)
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# Making some asserts:
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assert callable_provider_delegate1() is callable_provider
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assert callable_provider_delegate2() is callable_provider
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