python-dependency-injector/examples/external_dependency.py

55 lines
1.4 KiB
Python

"""
Concept example of objects catalogs.
"""
from objects import AbstractCatalog
from objects.providers import Singleton, NewInstance, ExternalDependency
from objects.injections import InitArg, Attribute
import sqlite3
# Some example classes.
class ObjectA(object):
def __init__(self, db):
self.db = db
class ObjectB(object):
def __init__(self, a, db):
self.a = a
self.db = db
# Catalog of objects providers.
class Catalog(AbstractCatalog):
"""
Objects catalog.
"""
database = ExternalDependency(instance_of=sqlite3.Connection)
""" :type: (objects.Provider) -> sqlite3.Connection """
object_a = NewInstance(ObjectA,
InitArg('db', database))
""" :type: (objects.Provider) -> ObjectA """
object_b = NewInstance(ObjectB,
InitArg('a', object_a),
InitArg('db', database))
""" :type: (objects.Provider) -> ObjectB """
# Satisfaction of external dependency.
Catalog.database.satisfy(Singleton(sqlite3.Connection,
InitArg('database', ':memory:'),
Attribute('row_factory', sqlite3.Row)))
# Catalog static provides.
a1, a2 = Catalog.object_a(), Catalog.object_a()
b1, b2 = Catalog.object_b(), Catalog.object_b()
# Some asserts.
assert a1 is not a2
assert b1 is not b2
assert a1.db is a2.db is b1.db is b2.db is Catalog.database()