Dependency Injector

Dependency injection framework for Python projects.

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Dependency Injector is a dependency injection framework for Python projects. It was designed to be unified, developer's friendly tool for managing any kind of Python objects and their dependencies in formal, pretty way.

Below is a list of some key features and points of Dependency Injector framework:

• Easy, smart, pythonic style.
• Obvious, clear structure.
• Memory efficiency.
• Thread safety.
• Semantic versioning.

Main idea of Dependency Injector is to keep dependencies under control.

Installation

Dependency Injector library is available on PyPi:

pip install dependency_injector

Documentation

Dependency Injector documentation is hosted on ReadTheDocs:

• Stable version
• Latest version

Examples

"""Concept example of `Dependency Injector`."""

import sqlite3
import dependency_injector as di


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(di.AbstractCatalog):
    """Catalog of providers."""

    database = di.Singleton(sqlite3.Connection,
                            database=':memory:')
    """:type: (di.Provider) -> sqlite3.Connection"""

    object_a_factory = di.Factory(ObjectA,
                                  db=database)
    """:type: (di.Provider) -> ObjectA"""

    object_b_factory = di.Factory(ObjectB,
                                  a=object_a_factory,
                                  db=database)
    """:type: (di.Provider) -> ObjectB"""


# Catalog static provides.
a1, a2 = Catalog.object_a_factory(), Catalog.object_a_factory()
b1, b2 = Catalog.object_b_factory(), Catalog.object_b_factory()

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.
@di.inject(a=Catalog.object_a_factory)
@di.inject(b=Catalog.object_b_factory)
@di.inject(database=Catalog.database)
def example(a, b, database):
    """Example callback."""
    assert a.db is b.db is database is Catalog.database()


example()

You can get more Dependency Injector examples in /examples directory on GitHub:

https://github.com/rmk135/dependency_injector

Feedback

Feel free to post questions, bugs, feature requests, proposals etc. on Dependency Injector GitHub Issues:

https://github.com/rmk135/dependency_injector/issues

Your feedback is quite important!