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35 lines
1.4 KiB
ReStructuredText
35 lines
1.4 KiB
ReStructuredText
Writing of custom providers
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---------------------------
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.. module:: dependency_injector.providers
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List of *Dependency Injector* providers could be widened with custom providers.
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Below are some tips and recommendations that have to be met:
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1. Every custom provider has to extend base provider class -
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:py:class:`Provider`.
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2. Cusom provider's ``__init__()`` could be overriden, but parent's
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initializer (:py:meth:`Provider.__init__`) has to be called.
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3. Providing strategy has to be implemented in custom provider's
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:py:meth:`Provider._provide` method. All ``*args`` & ``**kwargs``
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that will be recieved by :py:meth:`Provider.__call__` will be
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transefed to custom provider's :py:meth:`Provider._provide`.
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4. If custom provider is based on some standard providers, it is better to
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use delegation of standard providers, then extending of them.
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5. If custom provider defines any attributes, it is good to list them in
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``__slots__`` attribute (as *Dependency Injector* does). It can save
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some memory.
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6. If custom provider deals with injections, it is strongly recommended
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to be consistent with :py:class:`Factory`, :py:class:`Singleton` and
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:py:class:`Callable` providers style.
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Example:
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.. image:: /images/providers/custom_provider.png
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:width: 100%
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:align: center
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.. literalinclude:: ../../examples/providers/custom_factory.py
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:language: python
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