python-dependency-injector/examples/concept.py

61 lines
1.3 KiB
Python

"""
Concept example of objects catalogs.
"""
import objects
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 Catalog(objects.Catalog):
"""
Objects catalog.
"""
database = objects.Singleton(provides=sqlite3.Connection,
database='example.db')
""" :type: (objects.Provider) -> sqlite3.Connection """
object_a = objects.NewInstance(provides=A,
db=database)
""" :type: (objects.Provider) -> A """
object_b = objects.NewInstance(provides=B,
a=object_a,
db=database)
""" :type: (objects.Provider) -> B """
# Catalog injection into consumer class.
class Consumer(object):
catalog = Catalog(Catalog.object_a,
Catalog.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 = Catalog.object_a()
b2 = 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