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42 lines
1.6 KiB
ReStructuredText
42 lines
1.6 KiB
ReStructuredText
External dependency providers
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.. module:: dependency_injector.providers
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:py:class:`ExternalDependency` provider can be useful for development of
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self-sufficient libraries / modules / applications that has required external
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dependencies.
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For example, you have created self-sufficient library / module / application,
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that has dependency on *database connection*.
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Second step you want to do is to make this software component to be easy
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reusable by wide amount of developers and to be easily integrated into many
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applications.
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It may be good idea, to move all external dependencies (like
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*database connection*) to the top level and make them to be injected on your
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software component's initialization. It will make third party developers feel
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themselves free about integration of yours component in their applications,
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because they would be able to find right place / right way for doing this
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in their application's architectures.
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At the same time, you can be sure, that your external dependency will be
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satisfied with appropriate instance.
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Example:
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.. note::
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Class ``UserService`` is a part of some library. ``UserService`` has
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dependency on database connection, which can be satisfied with any
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DBAPI 2.0 database connection. Being a self-sufficient library,
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``UserService`` doesn't hardcode any kind of database management logic.
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Instead of this, ``UserService`` has external dependency, that has to
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be satisfied by cleint's code, out of library's scope.
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.. image:: /images/providers/external_dependency.png
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.. literalinclude:: ../../examples/providers/external_dependency.py
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:language: python
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