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alluka#

A type based dependency injection framework for Python 3.9+.

Injected module-attribute #

Injected = typing.Annotated[_T, InjectedTypes.TYPE]

Type alias used to declare a keyword argument as requiring an injected type.

If a union (e.g. typing.Union[A, B], A | B, typing.Optional[A]) is passed then each type in the union will be tried separately rather than the literal type, allowing for resolving A | B to the value set by set_type_dependency(B, ...).

If a union has None as one of its types (including Optional[T]) then None will be passed for the parameter if none of the types could be resolved using the linked client.

Note

This is a typing.Annotated alias and the behaviour for nested Annotated types may be found at the docs for it typing.Annotated.

AllukaError #

Bases: Exception

Base class for the custom errors raised by Alluka.

AsyncSelfInjecting #

Bases: alluka.AsyncSelfInjecting[_CallbackSigT]

Class used to link a sync function to a client to make it self-injecting.

Examples:

async def callback(database: Database = alluka.inject(type=Database)) -> None:
    await database.do_something()
...

client = alluka.Client()
injecting_callback = alluka.AsyncSelfInjecting(callback, client)
await injecting_callback()

Alternatively alluka.abc.Client.as_async_self_injecting may be used:

client = alluka.Client()

@client.as_async_self_injecting
async def callback(database: Database = alluka.inject(type=Database)) -> None:
    ...

__init__ #

__init__(client, callback)

Initialise a self injecting callback.

Parameters:

  • client (alluka.Client) –

    The injection client to use to resolve dependencies.

  • callback (alluka.abc.CallbackSig) –

    The callback to make self-injecting.

    This may be sync or async.

Raises:

  • ValueError –

    If callback has any injected arguments which can only be passed positionally.

BasicContext #

Bases: alluka.Context

Basic implementation of alluka.abc.Context.

__init__ #

__init__(client)

Initialise a basic injection context.

Parameters:

  • client (alluka.Client) –

    The injection client this context is bound to.

Client #

Bases: alluka.Client

Standard implementation of a dependency injection client.

This is used to track type dependencies and execute callbacks.

__init__ #

__init__(*, introspect_annotations=True)

Initialise an injector client.

InjectedDescriptor #

Bases: typing.Generic[_T]

Descriptor used to a declare keyword-argument as requiring an injected dependency.

This is the type returned by alluka.inject.

callback instance-attribute #

callback: typing.Optional[alluka.CallbackSig[_T]] = callback

The callback to use to resolve the parameter's value.

If this is None then this is a type dependency.

type instance-attribute #

type: typing.Optional[_TypeT[_T]] = type

The type to use to resolve the parameter's value.

If both this and callback are None, then this is a type dependency and the type will be inferred from the parameter's annotation.

__init__ #

__init__(*, callback=None, type=None)

Initialise an injection default descriptor.

Note

If neither type or callback is provided, an injected type will be inferred from the argument's annotation.

Parameters:

  • callback (typing.Optional[alluka.CallbackSig[_T]]) –

    The callback to use to resolve the dependency.

    If this callback has no type dependencies then this will still work without an injection context but this can be overridden using alluka.abc.Client.set_callback_override.

  • type (typing.Optional[_TypeT[_T]]) –

    The type of the dependency to resolve.

    If a union (e.g. typing.Union[A, B], A | B, typing.Optional[A]) is passed for type then each type in the union will be tried separately after the litarl union type is tried, allowing for resolving A | B to the value set by set_type_dependency(B, ...).

    If a union has None as one of its types (including Optional[T]) then None will be passed for the parameter if none of the types could be resolved using the linked client.

Raises:

  • ValueError –

    If both callback and type are provided.

MissingDependencyError #

Bases: AllukaError

Error raised when a dependency couldn't be found.

dependency_type instance-attribute #

dependency_type: typing.Any = dependency_type

Type of the missing dependency.

message instance-attribute #

message: str = message

The error's message.

__init__ #

__init__(message, dependency_type)

Initialise a missing dependency error.

Parameters:

  • message (str) –

    The error message.

SelfInjecting #

Bases: alluka.SelfInjecting[_SyncCallbackT]

Class used to link a sync function to a client to make it self-injecting.

Note

This executes the callback synchronously and therefore will error if any of the callback's dependencies are async.

Examples:

async def callback(database: Database = alluka.inject(type=Database)) -> None:
    await database.do_something()
...

client = alluka.Client()
injecting_callback = alluka.SelfInjecting(callback, client)
await injecting_callback()

Alternatively alluka.abc.Client.as_self_injecting may be used:

client = alluka.Client()

@client.as_self_injecting
async def callback(database: Database = alluka.inject(type=Database)) -> None:
    ...

__init__ #

__init__(client, callback)

Initialise a sync self injecting callback.

Parameters:

  • client (alluka.Client) –

    The injection client to use to resolve dependencies.

  • callback (collections.abc.Callable) –

    The callback to make self-injecting.

Raises:

  • ValueError –

    If callback has any injected arguments which can only be passed positionally.

SyncOnlyError #

Bases: AllukaError

Error raised when trying to execute async DI in a sync context.

inject #

inject(*, callback=None, type=None)

Decare a keyword-argument as requiring an injected dependency.

This may be assigned to an arugment's default value to declare injection or as a part of its Annotated metadata.

Note

If neither type nor callback is provided, an injected type will be inferred from the argument's annotation.

Examples:

async def callback(
    # Here we require an implementation of the type `Component` to be
    # injected.
    injected_type: Component = alluka.inject(type=Component)
    # Here we inject an out-of-scope callback which itself is taking
    # advantage of type injectioallukan.
    callback_result: ResultT = alluka.inject(callback=injected_callback)
) -> None:
    raise NotImplementedError

...
# where client is an `alluka.Client` instance.
result = await client.call_with_async_di(callback)

Parameters:

  • callback (typing.Optional[alluka.CallbackSig[_T]]) –

    The callback to use to resolve the dependency.

    If this callback has no type dependencies then this will still work without an injection context but this can be overridden using alluka.abc.Client.set_callback_override.

  • type (typing.Any) –

    The type of the dependency to resolve.

    If a union (e.g. typing.Union[A, B], A | B, typing.Optional[A]) is passed for type then each type in the union will be tried separately rather than the literal type, allowing for resolving A | B to the value set by set_type_dependency(B, ...).

    If a union has None as one of its types (including Optional[T]) then None will be passed for the parameter if none of the types could be resolved using the linked client.

Raises:

  • ValueError –

    If both type and callback are provided.