python-dependency-injector/docs/catalogs/declarative.rst
2015-11-29 23:30:48 +02:00

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Declarative catalogs
--------------------
.. currentmodule:: dependency_injector.catalogs
:py:class:`DeclarativeCatalog` is a catalog of providers that could be
defined in declarative manner. It should cover most of the cases when list
of providers that would be included in catalog is deterministic (catalog
will not change its structure in runtime).
Declarative catalogs have to extend base declarative catalog class -
:py:class:`dependency_injector.catalogs.DeclarativeCatalog`.
Declarative catalog's providers have to be defined like catalog's class
attributes. Every provider in catalog has name. This name should follow
``some_provider`` convention, that is standard naming convention for
attribute names in Python.
.. note::
Declarative catalogs have several features that could be useful
for some kind of operations on catalog's providers, please visit API
documentation for getting full list of features -
:py:class:`dependency_injector.catalogs.DeclarativeCatalog`.
.. note::
It might be useful to add such
``""":type: dependency_injector.providers.Provider -> Object1"""``
docstrings just on the next line after provider's definition. It will
help code analyzing tools and IDE's to understand that variable above
contains some callable object, that returns particular instance as a
result of its call.
Here is an simple example of defining declarative catalog with several
factories:
.. image:: /images/catalogs/declarative.png
:width: 85%
:align: center
.. literalinclude:: ../../examples/catalogs/declarative.py
:language: python
Example of declarative catalogs inheritance:
.. image:: /images/catalogs/declarative_inheritance.png
:width: 100%
:align: center
.. literalinclude:: ../../examples/catalogs/declarative_inheritance.py
:language: python
Example of declarative catalog's provider injections:
.. image:: /images/catalogs/declarative_injections.png
:width: 100%
:align: center
.. literalinclude:: ../../examples/catalogs/declarative_injections.py
:language: python