mirror of
https://github.com/ets-labs/python-dependency-injector.git
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434 lines
10 KiB
Markdown
434 lines
10 KiB
Markdown
Objects
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=======
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Python catalogs of objects providers.
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Example of objects catalog definition and usage:
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```python
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"""
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Concept example of objects catalogs.
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"""
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from objects import AbstractCatalog
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from objects.providers import Singleton, NewInstance
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from objects.injections import 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 Catalog(AbstractCatalog):
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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 = Catalog.object_a(), Catalog.object_a()
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b1, b2 = Catalog.object_b(), Catalog.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 Catalog.database()
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# Dependencies injection (The Python Way) into class.
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class Consumer(object):
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dependencies = Catalog(Catalog.object_a,
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Catalog.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=Catalog(Catalog.object_a,
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Catalog.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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```
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Example of overriding object providers:
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```python
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"""
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Concept example of objects overrides.
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"""
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from objects import AbstractCatalog, overrides
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from objects.providers import Singleton, NewInstance
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from objects.injections import InitArg, Attribute
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import sqlite3
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# Some example class.
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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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# Mock of example class.
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class ObjectAMock(ObjectA):
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pass
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# Catalog of objects providers.
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class Catalog(AbstractCatalog):
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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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# Overriding Catalog by SandboxCatalog with some mocks.
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@overrides(Catalog)
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class SandboxCatalog(Catalog):
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"""
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Sandbox objects catalog with some mocks.
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"""
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object_a = NewInstance(ObjectAMock,
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InitArg('db', Catalog.database))
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""" :type: (objects.Provider) -> ObjectA """
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# Catalog static provides.
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a1 = Catalog.object_a()
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a2 = Catalog.object_a()
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# Some asserts.
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assert isinstance(a1, ObjectAMock)
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assert isinstance(a2, ObjectAMock)
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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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```
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Example of objects catalog external dependency:
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```python
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"""
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Concept example of objects catalogs.
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"""
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from objects import AbstractCatalog
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from objects.providers import Singleton, NewInstance, ExternalDependency
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from objects.injections import 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 Catalog(AbstractCatalog):
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"""
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Objects catalog.
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"""
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database = ExternalDependency(instance_of=sqlite3.Connection)
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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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# Satisfaction of external dependency.
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Catalog.database.satisfy(Singleton(sqlite3.Connection,
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InitArg('database', ':memory:'),
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Attribute('row_factory', sqlite3.Row)))
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# Catalog static provides.
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a1, a2 = Catalog.object_a(), Catalog.object_a()
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b1, b2 = Catalog.object_b(), Catalog.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 Catalog.database()
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```
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Example of objects catalog with scoped provider:
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```python
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"""
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Scoped provider examples.
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"""
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from objects import AbstractCatalog
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from objects.providers import Singleton, Scoped
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from objects.injections import InitArg, Attribute
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import sqlite3
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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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# Catalog of objects providers.
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class Catalog(AbstractCatalog):
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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 = Scoped(ObjectA,
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InitArg('db', database))
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""" :type: (objects.Provider) -> ObjectA """
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# Making scope using `with` statement.
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with Catalog.object_a as object_a_provider:
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object_a1 = object_a_provider()
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object_a2 = object_a_provider()
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assert object_a1 is object_a2
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assert object_a1.db is object_a2.db
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# Making another one scope using `with` statement.
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with Catalog.object_a as object_a_provider:
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object_a3 = object_a_provider()
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object_a4 = object_a_provider()
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assert object_a3 is object_a4
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assert object_a3.db is object_a4.db
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assert (object_a1 is not object_a3) and \
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(object_a1 is not object_a4)
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assert (object_a2 is not object_a3) and \
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(object_a2 is not object_a4)
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# Making one more scope using provider methods.
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Catalog.object_a.in_scope()
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object_a5 = Catalog.object_a()
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object_a6 = Catalog.object_a()
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Catalog.object_a.out_of_scope()
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assert object_a5 is object_a6
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assert object_a5.db is object_a6.db
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assert (object_a1 is not object_a3) and \
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(object_a1 is not object_a4) and \
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(object_a1 is not object_a5) and \
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(object_a1 is not object_a6)
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assert (object_a2 is not object_a3) and \
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(object_a2 is not object_a4) and \
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(object_a2 is not object_a5) and \
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(object_a2 is not object_a6)
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```
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Example of objects catalog with callable provider:
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```python
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"""
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Callable provider examples.
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"""
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from objects import AbstractCatalog
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from objects.providers import Singleton, Callable
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from objects.injections import Injection, InitArg, Attribute
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import sqlite3
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# Some example function.
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def consuming_function(arg, db):
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return arg, db
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# Catalog of objects providers.
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class Catalog(AbstractCatalog):
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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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consuming_function = Callable(consuming_function,
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Injection('db', database))
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""" :type: (objects.Provider) -> consuming_function """
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# Some calls.
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arg1, db1 = Catalog.consuming_function(1)
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arg2, db2 = Catalog.consuming_function(2)
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arg3, db3 = Catalog.consuming_function(3)
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# Some asserts.
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assert db1 is db2 is db3
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assert arg1 == 1
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assert arg2 == 2
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assert arg3 == 3
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```
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Example of objects catalog with config provider:
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```python
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"""
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Config provider examples.
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"""
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from objects import AbstractCatalog
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from objects.providers import Config, NewInstance
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from objects.injections import InitArg
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# Some example class.
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class ObjectA(object):
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def __init__(self, setting_one, setting_two, setting_three):
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self.setting_one = setting_one
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self.setting_two = setting_two
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self.setting_three = setting_three
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# Catalog of objects providers.
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class Catalog(AbstractCatalog):
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"""
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Objects catalog.
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"""
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config = Config()
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""" :type: (objects.Config) """
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object_a = NewInstance(ObjectA,
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InitArg('setting_one', config.SETTING_ONE),
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InitArg('setting_two', config.SETTING_TWO),
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InitArg('setting_three', config.GLOBAL.SETTING_THREE))
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""" :type: (objects.Provider) -> ObjectA """
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# Setting config value and making some tests.
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Catalog.config.update_from({
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'SETTING_ONE': 1,
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'SETTING_TWO': 2,
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'GLOBAL': {
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'SETTING_THREE': 3
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}
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})
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object_a1 = Catalog.object_a()
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assert object_a1.setting_one == 1
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assert object_a1.setting_two == 2
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assert object_a1.setting_three == 3
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# Changing config value one more time and making some tests.
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Catalog.config.update_from({
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'SETTING_ONE': 11,
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'SETTING_TWO': 22,
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'GLOBAL': {
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'SETTING_THREE': 33
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}
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})
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object_a2 = Catalog.object_a()
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assert object_a2.setting_one == 11
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assert object_a2.setting_two == 22
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assert object_a2.setting_three == 33
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assert object_a1.setting_one == 1
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assert object_a1.setting_two == 2
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assert object_a1.setting_three == 3
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```
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