Simple API

If you don’t want to dive into the details of “Injectors” and “Registries” you can use a subset of injectme’s capabilities called “Simple API”.

The “Simple API” consists of 4 functions: injectme.inject(), injectme.register(), injectme.register_factory() and injectme.clear_dependencies().

These functions are simply wrapping calls to single, global instance of injectme.Injector.

Example:

example.py

from injectme import (
    inject,
    register,
    register_factory,
    clear_dependencies,
)


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

    def __str__(self):
        return f"DependencyA: {self.name}"


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

    def __str__(self):
        return f"DependencyB: {self.name}"


# using inject to mark this class as a target for DI
@inject
class Example:
    dep_a: DependencyA
    dep_b: DependencyB

    def print_deps(self):
        print("Showing dependencies:")
        print(self.dep_a)
        print(self.dep_b)


# now it's time for setting up the injection

# register single instance for DependencyA
register(DependencyA, DependencyA("Alice"))

# register factory for DependencyB
def dep_b_factory():
    return DependencyB("Bob")

register_factory(DependencyB, dep_b_factory)

# see how it works
print("Creating Example instance")
example = Example()
example.print_deps()


# clear all deps and see how it breaks
print("Clearing dependencies")
clear_dependencies()
Example()

$ python3 example.py

Creating Example instance
Showing dependencies:
DependencyA: Alice
DependencyB: Bob
Clearing dependencies
Traceback (most recent call last):
    ...
injectme.errors.InjectionFailure: Failed to inject dependencies into <class '__main__.Example'>