python-dependency-injector/examples/concept.py
2015-01-10 11:24:25 +02:00

62 lines
1.4 KiB
Python

"""
Concept example of objects catalogs.
"""
from objects import Catalog, Singleton, NewInstance, InitArg, Attribute
import sqlite3
# Some example classes.
class A(object):
def __init__(self, db):
self.db = db
class B(object):
def __init__(self, a, db):
self.a = a
self.db = db
# Catalog of objects providers.
class AppCatalog(Catalog):
"""
Objects catalog.
"""
database = Singleton(sqlite3.Connection,
InitArg('database', ':memory:'),
Attribute('row_factory', sqlite3.Row))
""" :type: (objects.Provider) -> sqlite3.Connection """
object_a = NewInstance(A,
InitArg('db', database))
""" :type: (objects.Provider) -> A """
object_b = NewInstance(B,
InitArg('a', object_a),
InitArg('db', database))
""" :type: (objects.Provider) -> B """
# Catalog injection into consumer class.
class Consumer(object):
catalog = AppCatalog(AppCatalog.object_a,
AppCatalog.object_b)
def return_a_b(self):
return (self.catalog.object_a(),
self.catalog.object_b())
a1, b1 = Consumer().return_a_b()
# Catalog static provides.
a2 = AppCatalog.object_a()
b2 = AppCatalog.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