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https://github.com/ets-labs/python-dependency-injector.git
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57 lines
1.4 KiB
Python
57 lines
1.4 KiB
Python
"""Provider delegation example."""
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from objects import AbstractCatalog
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from objects.providers import Singleton
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from objects.providers import NewInstance
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from objects.injections import InitArg
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from objects.injections import Attribute
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import sqlite3
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class ObjectA(object):
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"""Example class ObjectA, that has dependency on database."""
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def __init__(self, db):
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"""Initializer."""
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self.db = db
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class ObjectB(object):
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"""Example class ObjectB, that has dependency on ObjectA provider."""
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def __init__(self, a_provider):
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"""Initializer."""
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self.a_provider = a_provider
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class Catalog(AbstractCatalog):
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"""Catalog of objects providers."""
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database = Singleton(sqlite3.Connection,
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InitArg('database', ':memory:'),
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Attribute('row_factory', sqlite3.Row))
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""":type: (objects.Provider) -> sqlite3.Connection"""
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object_a = NewInstance(ObjectA,
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InitArg('db', database))
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""":type: (objects.Provider) -> ObjectA"""
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object_b = Singleton(ObjectB,
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InitArg('a_provider', object_a.delegate()))
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""":type: (objects.Provider) -> ObjectB"""
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# Catalog static provides.
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b = Catalog.object_b()
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a1, a2 = b.a_provider(), b.a_provider()
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# Some asserts.
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assert a1 is not a2
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assert a1.db is a2.db is Catalog.database()
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