GhostOS Container

IoC container for GhostOS.

IoC Container

GhostOS follows the concept of interface-oriented programming to build the project. Most modules are divided into interface and implementation. Register and get implementations by IoC Container.

About IoC: Inverse of Control

Why?

In Java and PHP projects, IoC Container is widely used. For example:

• Java Spring
• PHP Laravel

However, in Python projects, it is rarely used, often replaced by singletons and factory methods.

GhostOS introduces the IoC Container, with the most fundamental motivation being to achieve interface-oriented programming and runtime dependency injection. Taking SpheroBoltGPT as an example:

from ghostos.prototypes.spherogpt.bolt import (
    RollFunc,
    Ball,
    Move,
    LedMatrix,
    Animation,
)
from ghostos_moss import Moss as Parent


class Moss(Parent):
    body: Ball
    """your sphero ball body"""

    face: LedMatrix
    """you 8*8 led matrix face"""

这部分代码会被自动反射成 prompt 提供给大模型. 但其中的 Ball 和 LedMatrix 在项目正式启动前都不应该实例化. 尤其是当一个 Meta-Agent 需要分析这段代码时, 它不应该在阅读代码时导致创建和 Sphero Bolt 的连接.

所以 Ball 和 LedMatrix 可以用抽象来设计:

This part of the code will be automatically reflected as a prompt provided to the large language model. However, Ball and LedMatrix should not be instantiated before the project officially starts.

Especially when a Meta-Agent needs to analyze this code, it should not cause the creation of a connection with Sphero Bolt while reading the code. Therefore, Ball and LedMatrix can be designed abstractly:

class Ball(ABC):
    """
    Sphero bolt body (which is a rolling ball) control interface.
    """

    @abstractmethod
    def new_move(
            self,
            *,
            run: bool = False,
            animation: Optional[Animation] = None,
    ) -> Move:
        """
        create a new Move instance, to define a sequence of movements.
        :param run: run immediately if True, otherwise the move will not execute until run it.
        :param animation: if animation is not none, it will be played while run the move.
        """
        pass

    @abstractmethod
    def run(self, move: Move, stop_at_first: bool = True) -> None:
        """
        run the bolt ball movement
        :param move: the Move instance that defined the movements by calling it methods one by one.
        :param stop_at_first: shall stop any movement of the ball before executing the new move?
        """
        pass

The actual instances are only injected through the container during runtime:

Basic Usage

from abc import ABC, abstractmethod
from typing import Type
from ghostos_container import Container, Provider


def test_container_baseline():
    class Abstract(ABC):
        @abstractmethod
        def foo(self) -> int:
            pass

    class Foo(Abstract):
        count = 0

        def foo(self) -> int:
            self.count += 1
            return self.count

    container = Container()

    # set instance
    foo = Foo()
    container.set(Foo, foo)
    assert container.get(Foo) is foo

Provider

Implementations registered through the Container.set method are singletons. In scenarios oriented towards composition, a factory method is needed to obtain dependencies and generate instances. In this case, ghostos_container.Provider can be used:

from abc import ABC, abstractmethod
from typing import Type
from ghostos_container import Container, Provider


def test_container_baseline():
    class Abstract(ABC):
        @abstractmethod
        def foo(self) -> int:
            pass

    class Foo(Abstract):
        def __init__(self, count):
            self.count = count

        def foo(self) -> int:
            return self.count

    class FooProvider(Provider):

        def singleton(self) -> bool:
            return True

        def contract(self) -> Type[Abstract]:
            return Abstract

        def factory(self, con: Container) -> Abstract:
            # get dependencies from con
            count = con.get("count")
            return Foo(count)

    # register
    container = Container()
    container.set("count", 123)
    container.register(FooProvider())

    # get instance
    foo = container.force_fetch(Abstract)
    assert isinstance(foo, Foo)
    assert foo.foo() is 123

And syntax sugar ghostos_container.provide could decorate a factory function into a Provider.

from abc import ABC, abstractmethod
from ghostos_container import Container, provide


class Abstract(ABC):
    @abstractmethod
    def foo(self) -> int:
        pass


class Foo(Abstract):
    def __init__(self, count):
        self.count = count

    def foo(self) -> int:
        return self.count


@provide(Abstract, singleton=True)
def foo_factory(self, con: Container) -> Abstract:
    # get dependencies from con
    count = con.get("count")
    return Foo(count)


# register
container = Container()
container.set("count", 123)
container.register(foo_factory)

# get instance
foo = container.force_fetch(Abstract)
assert isinstance(foo, Foo)
assert foo.foo() is 123

Inheritance

Container is inheritable:

from ghostos_container import Container

container = Container(name="parent")
container.set("foo", "foo")

child_container = Container(parent=container, name="child")
assert child_container.get("foo") == "foo"

When a descendant Container looks for a registered dependency and does not find it, it will recursively search for it in the parent Container.

And Provider can also be inherited by child container:

from ghostos_container import Provider


class MyProvider(Provider):

    def inheritable(self) -> bool:
        return not self.singleton()

All inheritable providers registered in the parent container are also automatically registered in the child container.

Bootstrap and Shutdown

A Container can also serve as a container for starting and shutting down components.

from ghostos_container import Bootstrapper, Container

container = Container()


class MyBootstrapper(Bootstrapper):
    def bootstrap(self, container: Container) -> None:
        # do something 
        ...


# start all the bootstrapper
container.bootstrap()

Bootstrapper can also be defined by ghostos_container.BootstrapProvider.

Container useContainer.add_shutdown register shutdown callback, they are called when Container.shutdown is called.

Container Tree

In App, there are Containers at different levels, with each Container inheriting from its parent Container and managing its own independent set of dependencies.

• When a child Container registers dependencies, it does not pollute the parent or sibling Containers.
• When a child Container is destroyed, it does not affect the parent or sibling Containers.

In this way, Container is similar to Python contextvars, which can manage a separate execution context, for example:

• Process level
• Thread level
• Coroutine level