python-dependency-injector/docs/catalogs/overriding.rst
2015-11-10 10:42:29 +02:00

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Overriding of catalogs
----------------------
Catalogs can be overridden by other catalogs. This, actually, means that
all of the providers from overriding catalog will override providers with the
same names in overridden catalog.
There are two ways to override catalog by another catalog:
- Use ``di.DeclarativeCatalog.override(AnotherCatalog)`` method.
- Use ``@di.override(AnotherCatalog)`` class decorator.
Example of overriding catalog using ``di.DeclarativeCatalog.override()``
method:
.. literalinclude:: ../../examples/catalogs/override.py
:language: python
Example of overriding catalog using ``@di.override()`` decorator:
.. literalinclude:: ../../examples/catalogs/override_decorator.py
:language: python
Also there are several useful methods and properties that help to work with
catalog overridings:
- ``di.DeclarativeCatalog.is_overridden`` - read-only, evaluated in runtime,
property that is set to True if catalog is overridden.
- ``di.DeclarativeCatalog.last_overriding`` - reference to the last overriding
catalog, if any.
- ``di.DeclarativeCatalog.overridden_by`` - tuple of all overriding catalogs.
- ``di.DeclarativeCatalog.reset_last_overriding()`` - reset last overriding
catalog.
- ``di.DeclarativeCatalog.reset_override()`` - reset all overridings for all
catalog providers.