from __future__ import absolute_import, unicode_literals

from contextlib import contextmanager
import sys

from django.utils.encoding import force_text


class NullFile(object):
    def write(self, string):
        """Writes here go nowhere"""


@contextmanager
def mute_stdout():
    stdout_old = sys.stdout
    sys.stdout = NullFile()
    yield
    sys.stdout = stdout_old


def as_id_list(items):
    return ','.join(
        [force_text(item.pk) for item in items]
    )