autoinject 1.1.0

Automated dependency injection for Python

Autoinject

A clean, simple framework for automatically injecting dependencies into objects and functions based around Python's type-hinting system. The framework provides caching of injectable objects, though this may be disabled on a class-by-class basis. It also supports managing independent caches for different contexts.

Define Injectable Classes

# Easy mode

from autoinject import injector

@injector.injectable
class MyInjectableClass:

    # __init__() should have no additional required arguments
    def __init__(self):
        pass


# Hard mode, must specify the fully-qualified name of the class,
# but gain control over the arguments

@injector.register("example.MyInjectableClass", os.environ("MY_CONFIG_FILE"))
class MyInjectableClass:

    def __init__(self, config_file):
        # we receive os.environ("MY_CONFIG_FILE") as config_file here
        # positional and keyword arguments to @injector.register() are supported
        pass

Inject Objects With Decorators

# Decorate with @injector.inject for functions/methods:

@injector.inject
def inject_me(param1, param2, injected_param: MyInjectableClass):
    # injected_param is set to an instance of MyInjectableClass
    pass

# Omit the injected parameters when calling it:

inject_me("arg1", "arg2")


# For classes, use @injector.construct to set instance attributes 
# based on the class attributes   
class InjectMe:

    injected_attribute: MyInjectableClass = None

    @injector.construct
    def __init__(self):
        # self.injected_attribute is set to an instance of MyInjectableClass
        pass

# No need to do anything special here:
obj = InjectMe()
# obj.injected_attribute is set by the decorator before __init__() is called.

Read the full documentation for more details.

Changelog

v1.1.0

• Injectable objects may now define a __cleanup__() method which will be invoked when the global cache or context cache is cleared.
• Note that __cleanup__() IS NOT INVOKED for one-time use objects at the moment, but this is planned as a feature.

v1.0.1

• Inherited injectable class members are now supported properly

v1.0.0

• Official initial release
• Added support for @injector.injectable_global which registers with GLOBAL cache instead of context-specific cache
• Added support for @injector.injectable_nocache which registers with NO_CACHE instead
• Added support for injector.override() as a helper function to replace one constructor with another.
• Added support for any constructor argument (e.g. via override() or register_constructor()) to be specified by fully-qualified Python name (e.g. package.module.MyInjectableClass) to better support systems where injected classes are specified by name.
• Fixed a bug whereby the cache wasn't cleared

v0.2.2

• Fixed a bug for injection when a non-truthy default value needed to be used.

v0.2.1

• Fixed a bug in Python 3.8 and 3.9 where entry_points(group=?) was not supported

v0.2.0

• Objects with a cache strategy of CONTEXT_CACHE will now have separate instances within threads
• Added injector.get() as a fast way to get the object that would be injected (useful if operating outside of a function or method)
• Added injector.register_constructor() as a wrapper to register a class in a non-decorated fashion
• Added the entry point autoinject.injectables to directly register injectable classes
• Added the entry point autoinject.registrars
• Support for overriding injectables and for injecting functions
• Added a weight keyword argument to register() and register_construct() to control overriding order
• There is now a cleanup() function in the ContextManager() class which triggers informant objects to check for old items that are no longer needed. This was added mostly to support the thread-based context informant, since it has no easy way of calling destroy() whenever the thread ends (unless one manually calls it). It is the best practice if you can call destroy() directly whenever a context ceases to exist instead of relying on cleanup().