LazyCollectionMixin

lazy_collection.py

class LazyCollectionMixin(object):
    __len__ = new_method_proxy(len)
    __contains__ = new_method_proxy(operator.contains)

    def __iter__(self):
        # Don't define this as
        #   __iter__ = new_method_proxy(iter)
        # because that creates a method which doesn't call yield,
        # so it executes setup immediately.
        if self._wrapped is empty:
            self._setup()
        for x in self._wrapped:
            yield x

    def __reduce_ex__(self, version):
        if self._wrapped is empty:
            self._setup()
        return self._wrapped.__reduce_ex__(version)

    def __reduce__(self):
        if self._wrapped is empty:
            self._setup()
        return self._wrapped.__reduce__()


class SimpleLazyCollection(LazyCollectionMixin, SimpleLazyObject):
    pass