2.6 KiB
2.6 KiB
Objects
Python catalogs of objects providers
Example:
"""Concept example of `Objects`."""
from objects.catalog import AbstractCatalog
from objects.providers import Singleton
from objects.providers import NewInstance
from objects.injections import KwArg
from objects.injections import Attribute
from objects.injections import inject
import sqlite3
class ObjectA(object):
"""Example class ObjectA, that has dependency on database."""
def __init__(self, db):
"""Initializer."""
self.db = db
class ObjectB(object):
"""Example class ObjectB, that has dependencies on ObjectA and database."""
def __init__(self, a, db):
"""Initializer."""
self.a = a
self.db = db
class Catalog(AbstractCatalog):
"""Catalog of objects providers."""
database = Singleton(sqlite3.Connection,
KwArg('database', ':memory:'),
Attribute('row_factory', sqlite3.Row))
""":type: (objects.Provider) -> sqlite3.Connection"""
object_a = NewInstance(ObjectA,
KwArg('db', database))
""":type: (objects.Provider) -> ObjectA"""
object_b = NewInstance(ObjectB,
KwArg('a', object_a),
KwArg('db', database))
""":type: (objects.Provider) -> ObjectB"""
# Catalog static provides.
a1, a2 = Catalog.object_a(), Catalog.object_a()
b1, b2 = Catalog.object_b(), Catalog.object_b()
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()
# Example of inline injections.
@inject(KwArg('a', Catalog.object_a))
@inject(KwArg('b', Catalog.object_b))
@inject(KwArg('database', Catalog.database))
def example(a, b, database):
assert a.db is b.db is database is Catalog.database()
example()