Deps Draft

deps.py

import settings


class DepsResolver():
    """Resolves low level implementation from the config at the time the class
    is instantiated by returning the low level class.
    """

    def __new__(cls, name):
        cap_name = name.capitalize()
        key = "%sImplementationModule" % name
        impl_loc = settings[key]
        impl_module = __import__(impl_loc, globals(), locals(), [cap_name], -1)
        impl_cls = get(cap_name, impl_module)
        return impl_cls.__new__(cls)


class LazyDepsResolver():
    """Resolves low level implementation from the config at the time a method
    is called by calling the low level method.
    """

    def __init__(self, name):
        self.name = name

    def __getattr__(self, attr):
        class Resolver:
            """Delay resolving the implementation until any arguments
            potentially being passed to it can be inspected for an
            implementation override.
            """
            def __init__(self, attr):
                self.attr = attr

            def __call__(self, *args, **kwargs):
                """Inspects any (k)wargs for overrides, and finally resolves
                which component should be used to implement thi attribute.
                """
                name = kwargs.get("force_api_impl", self.name)
                impl = DepsResolver(name)
                impl.__getattribute__(self.attr)(*args, **kwargs)

        return Resolver(attr)


class WebService(LazyDepsResolver):
    """Add the URI field so our web framework to knows when to dispatch a
    request.
    """

    def __init__(self, name, uri):
        super(SocorroWebService, self).__init__(name)
        self.uri = uri

# internal use example:
# finding current products
product_internal = DepsResolver(name = "product")

# web service example:
# create the search service
search_service = WebService(name = "search", uri = "/search/([^/.]*)/(.*)")