tests/seq.py

demandimport: import sub-module relatively as expected (issue5208)

Before this patch, importing sub-module might (1) fail or (2) success
but import incorrect module, because demandimport tries to import
sub-module with level=-1 (on Python 2.x) or level=0 (on Python 3.x),
which is default value of "level" argument at construction of
"_demandmod" proxy object.

  (1) on Python 3.x, importing sub-module always fails to import
      existing sub-module

  (2) both on Python 2.x and 3.x, importing sub-module might import
      same name module on root level unintentionally

      On Python 2.x, existing sub-module is prior to this unexpected
      module. Therefore, this problem hasn't appeared.

To import sub-module relatively as expected, this patch specifies "1"
as import level explicitly at construction of "_demandmod" proxy
object for sub-module.

#!/usr/bin/env python
#
# A portable replacement for 'seq'
#
# Usage:
#   seq STOP              [1, STOP] stepping by 1
#   seq START STOP        [START, STOP] stepping by 1
#   seq START STEP STOP   [START, STOP] stepping by STEP

from __future__ import absolute_import, print_function
import sys

start = 1
if len(sys.argv) > 2:
    start = int(sys.argv[1])

step = 1
if len(sys.argv) > 3:
    step = int(sys.argv[2])

stop = int(sys.argv[-1]) + 1

for i in xrange(start, stop, step):
    print(i)