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https://github.com/ets-labs/python-dependency-injector.git
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100 lines
2.5 KiB
Python
100 lines
2.5 KiB
Python
"""
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Concept example of objects catalogs.
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"""
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from objects import Catalog, Singleton, NewInstance, InitArg, Attribute
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import sqlite3
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# Some example classes.
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class ObjectA(object):
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def __init__(self, db):
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self.db = db
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class ObjectB(object):
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def __init__(self, a, db):
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self.a = a
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self.db = db
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# Catalog of objects providers.
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class AppCatalog(Catalog):
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"""
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Objects catalog.
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"""
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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 = NewInstance(ObjectB,
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InitArg('a', object_a),
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InitArg('db', database))
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""" :type: (objects.Provider) -> ObjectB """
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# Catalog static provides.
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a1, a2 = AppCatalog.object_a(), AppCatalog.object_a()
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b1, b2 = AppCatalog.object_b(), AppCatalog.object_b()
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# Some asserts.
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assert a1 is not a2
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assert b1 is not b2
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assert a1.db is a2.db is b1.db is b2.db is AppCatalog.database()
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# Dependencies injection (The Python Way) into class.
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class Consumer(object):
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dependencies = AppCatalog(AppCatalog.object_a,
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AppCatalog.object_b)
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def test(self):
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a1 = self.dependencies.object_a()
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a2 = self.dependencies.object_a()
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b1 = self.dependencies.object_b()
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b2 = self.dependencies.object_b()
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# Some asserts.
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assert a1 is not a2
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assert b1 is not b2
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assert a1.db is a2.db is b1.db is b2.db
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try:
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self.dependencies.database()
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except AttributeError:
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pass
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else:
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raise Exception('Database is not listed as a dependency')
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Consumer().test()
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# Dependencies injection (The Python Way) into a callback.
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def consumer_callback(dependencies=AppCatalog(AppCatalog.object_a,
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AppCatalog.object_b)):
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a1 = dependencies.object_a()
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a2 = dependencies.object_a()
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b1 = dependencies.object_b()
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b2 = dependencies.object_b()
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# Some asserts.
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assert a1 is not a2
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assert b1 is not b2
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assert a1.db is a2.db is b1.db is b2.db
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try:
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dependencies.database()
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except AttributeError:
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pass
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else:
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raise Exception('Database is not listed as a dependency')
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