Source code for linkd.context

# -*- coding: utf-8 -*-
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from __future__ import annotations

__all__ = ["Context", "ContextRegistry", "Contexts", "DefaultContainer", "global_context_registry"]

import typing as t

from linkd import container

Context = t.NewType("Context", str)
"""
Type representing a dependency injection context. Used for labelling containers so that they
can be accessed using method injection if required. You can create and use your own contexts by
creating an instance of this type.
"""

DefaultContainer = t.NewType("DefaultContainer", container.Container)
"""Injectable type representing the dependency container for the default context."""


class ContextRegistry:
    __slots__ = ("_contexts",)

    def __init__(self) -> None:
        self._contexts: dict[Context, type[container.Container] | None] = {}

    def register(self, ns: str, linked_type: type[container.Container] | None = None) -> Context:
        self._contexts[c := Context(ns)] = linked_type
        return c

    def unregister(self, context: Context) -> None:
        del self._contexts[context]

    def type_for(self, context: Context) -> type[container.Container] | None:
        if context in self._contexts:
            return self._contexts[context]
        # TODO - maybe error that context has not been registered?
        return None


global_context_registry: ContextRegistry = ContextRegistry()




@t.final
class Contexts:
    """Collection of the dependency injection context values linkd uses."""

    __slots__ = ()

    DEFAULT = global_context_registry.register("linkd.contexts.default", DefaultContainer)
    """The base DI context - ALL other contexts are built with this as the parent."""