Injector

The injectme.Injector is on of the two core classes used by injectme. Injector’s responsiblity is to perform injection on specified class using dependencies from injectme.DependenciesRegistry.

injectme.Injector is a callable acting like a class decorator and can be used as such. Each decorated class will have it’s dependencies assigned as an instance attributes just before calling the __init__() method.

The injectme.inject() function is a shortcut for calling appropriate methods on a single global Injector instance created by injectme to provide Simple API.

injectme.Injector can be created using custom registry. If there’s no registry passed to __init__(), new instance injectme.DependenciesRegistry is automatically created and can be reached by using injectme.Injector.registry() property.

Example:

example.py

from injectme import Injector


class Dependency:
    def __init__(self, name):
        self.name = name


injector = Injector()

# used as a decorator
@injector
class ExampleA:
    dep: Dependency

    def show_dep(self):
        print(f"I am A and I have dependency {self.dep.name}")


class ExampleB:
    dep: Dependency

    def show_dep(self):
        print(f"I am B and I have dependency {self.dep.name}")


# or a simple callable
injector(ExampleB)


# dependencies have to be registered before instantiating depending
# classes
injector.registry.register_instance(
    Dependency, Dependency("some-dep")
)

ExampleA().show_dep()
ExampleB().show_dep()

$ python3 example.py

I am A and I have dependency some-dep
I am B and I have dependency some-dep new dependency