python-dependency-injector/examples/catalogs/override.py

"""Catalog overriding example."""

import collections
import dependency_injector as di


# Creating some example classes:
Object1 = collections.namedtuple('Object1', ['arg1', 'arg2'])
Object2 = collections.namedtuple('Object2', ['object1'])
ExtendedObject2 = collections.namedtuple('ExtendedObject2', [])


class Catalog(di.AbstractCatalog):

    """Providers catalog."""

    object1_factory = di.Factory(Object1,
                                 arg1=1,
                                 arg2=2)
    """:type: (di.Provider) -> Object1"""

    object2_factory = di.Factory(Object2,
                                 object1=object1_factory)
    """:type: (di.Provider) -> Object2"""


class AnotherCatalog(di.AbstractCatalog):

    """Another providers catalog."""

    object2_factory = di.Factory(ExtendedObject2)
    """:type: (di.Provider) -> ExtendedObject2"""


# Overriding `Catalog` with `AnotherCatalog`:
Catalog.override(AnotherCatalog)

# Creating some objects using overridden catalog:
object2_1 = Catalog.object2_factory()
object2_2 = Catalog.object2_factory()

# Making some asserts:
assert object2_1 is not object2_2

assert isinstance(object2_1, ExtendedObject2)
assert isinstance(object2_2, ExtendedObject2)