beckon

Stop trying to make fetch happen.

A typed component registry backed by zope.interface. Register components behind formal interfaces. Look them up without circular imports. Relationships are inferred and bidirectional.

Install

pip install beckon

For Django integration:

pip install beckon[django]

Quick Start

from zope.interface import Interface
from beckon import register, BeckonInterface

class _IService(Interface):
    pass

IService = BeckonInterface(_IService)

# register
register(IService, MyService, name='email')

# beckon
import beckon

beckon(IService, 'email')  # -> MyService
beckon(IService)           # -> [('email', MyService)]

The module itself is callable — import beckon; beckon(...) works without importing the function separately.

Django Integration

Add beckon.django to INSTALLED_APPS:

INSTALLED_APPS = [
    'beckon.django',
    # ...
]

This registers a name resolver for Django models (_meta.label_lower) and provides IModel:

from beckon import register
from beckon.django import IModel

from .models import Post

register(IModel, Post)

import beckon
from beckon.django import IModel

Post = beckon(IModel, 'posts.post')

Custom Interfaces with Relationships

from zope.interface import Interface
from beckon import BeckonInterface, register

class _ISerializer(Interface):
    pass

ISerializer = BeckonInterface(_ISerializer, infer_from='model')

Register a serializer and it automatically links to its model:

register(IModel, Post)
register(ISerializer, PostSerializer)  # infers from Meta.model

beckon(ISerializer, 'posts.post')  # -> PostSerializer
beckon(IModel, 'posts.post')       # -> Post (reverse works too)

Type Safety

Interfaces carry generic type information:

IModel: BeckonInterface[type[Model]] = BeckonInterface(_IModel)

mypy infers return types automatically:

beckon(IModel, 'auth.user')  # mypy sees: type[Model] | None

Define your own typed interfaces and get the same inference:

IPermission: BeckonInterface[type[BasePermission]] = BeckonInterface(_IPermission)
beckon(IPermission, 'is_admin')  # mypy sees: type[BasePermission] | None

License

BSD 2-Clause. See LICENSE.