python-dependency-injector/examples/scoped_provider.py
2015-03-10 00:55:38 +02:00

78 lines
2.0 KiB
Python

"""Scoped provider examples."""
from objects import AbstractCatalog
from objects.providers import Singleton
from objects.providers import Scoped
from objects.injections import InitArg
from objects.injections import Attribute
import sqlite3
class ObjectA(object):
"""Example class ObjectA, that has dependency on database."""
def __init__(self, db):
"""Initializer."""
self.db = db
class Catalog(AbstractCatalog):
"""Catalog of objects providers."""
database = Singleton(sqlite3.Connection,
InitArg('database', ':memory:'),
Attribute('row_factory', sqlite3.Row))
""":type: (objects.Provider) -> sqlite3.Connection"""
object_a = Scoped(ObjectA,
InitArg('db', database))
""":type: (objects.Provider) -> ObjectA"""
# Making scope using `with` statement.
with Catalog.object_a as object_a_provider:
object_a1 = object_a_provider()
object_a2 = object_a_provider()
assert object_a1 is object_a2
assert object_a1.db is object_a2.db
# Making another one scope using `with` statement.
with Catalog.object_a as object_a_provider:
object_a3 = object_a_provider()
object_a4 = object_a_provider()
assert object_a3 is object_a4
assert object_a3.db is object_a4.db
assert (object_a1 is not object_a3) and \
(object_a1 is not object_a4)
assert (object_a2 is not object_a3) and \
(object_a2 is not object_a4)
# Making one more scope using provider methods.
Catalog.object_a.in_scope()
object_a5 = Catalog.object_a()
object_a6 = Catalog.object_a()
Catalog.object_a.out_of_scope()
assert object_a5 is object_a6
assert object_a5.db is object_a6.db
assert (object_a1 is not object_a3) and \
(object_a1 is not object_a4) and \
(object_a1 is not object_a5) and \
(object_a1 is not object_a6)
assert (object_a2 is not object_a3) and \
(object_a2 is not object_a4) and \
(object_a2 is not object_a5) and \
(object_a2 is not object_a6)