I needed a way to register classes used in the application and wondered how easy it would be to hook into pyramids Configurator.scan method. Turns out it's not that hard.

gistfile1.py

"""play with venusian until you have a decorator that registers
classes with request.registry["service"] """
import unittest
import venusian
from pyramid.config import Configurator


class service(object):
    def __init__(self, name):
        self.name = name

    def __call__(self, cls):
        self.cls = cls
        venusian.attach(self.cls, self.on_scan)
        return self.cls

    def on_scan(self, scanner, name, ob):
        scanner.config.registry["services"][self.name] = self.cls


@service("testservice")
class MyTestService(object):
    pass


class TestServiceScanner(unittest.TestCase):
    def testScanner(self):
        config = Configurator()
        config.registry["services"] = {}
        config.scan()
        self.assertEquals(config.registry["services"]["testservice"], MyTestService)