Restore Python 3.x compatibility (raw_input() -> input())

See https://travis-ci.org/xolox/python-humanfriendly/jobs/28700750

humanfriendly.py

@@ -5,7 +5,7 @@
 # URL: https://humanfriendly.readthedocs.org
 
 # Semi-standard module versioning.
-__version__ = '1.9.3'
+__version__ = '1.9.4'
 
 # Standard library modules.
 import math
@@ -15,6 +15,13 @@
 import sys
 import time
 
+try:
+    # Python 2.x.
+    interactive_prompt = raw_input
+except NameError:
+    # Python 3.x.
+    interactive_prompt = input
+
 # Common disk size units, used for formatting and parsing.
 disk_size_units = (dict(prefix='b', divider=1, singular='byte', plural='bytes'),
                    dict(prefix='k', divider=1024**1, singular='KB', plural='KB'),
@@ -294,7 +301,7 @@ def prompt_for_choice(choices, default=None):
     # Loop until a valid choice is made.
     prompt = "Enter your choice as a number or unique substring (Ctrl-C aborts): "
     while True:
-        input = raw_input(prompt).strip()
+        input = interactive_prompt(prompt).strip()
         # Make sure the user entered something.
         if not input:
             if default is not None:

humanfriendly_tests.py

@@ -130,33 +130,34 @@ def test_spinner(self):
         self.assertEqual(sorted(set(lines)), sorted(lines))
 
     def test_prompt_for_choice(self):
+        interactive_prompt = humanfriendly.interactive_prompt
         try:
             # Choice selection by full string match.
-            humanfriendly.raw_input = lambda prompt: 'foo'
+            humanfriendly.interactive_prompt = lambda prompt: 'foo'
             self.assertEqual(humanfriendly.prompt_for_choice(['foo', 'bar']), 'foo')
             # Choice selection by substring input.
-            humanfriendly.raw_input = lambda prompt: 'f'
+            humanfriendly.interactive_prompt = lambda prompt: 'f'
             self.assertEqual(humanfriendly.prompt_for_choice(['foo', 'bar']), 'foo')
             # Choice selection by number.
-            humanfriendly.raw_input = lambda prompt: '2'
+            humanfriendly.interactive_prompt = lambda prompt: '2'
             self.assertEqual(humanfriendly.prompt_for_choice(['foo', 'bar']), 'bar')
             # Choice selection by going with the default.
-            humanfriendly.raw_input = lambda prompt: ''
+            humanfriendly.interactive_prompt = lambda prompt: ''
             self.assertEqual(humanfriendly.prompt_for_choice(['foo', 'bar'], default='bar'), 'bar')
             # Invalid substrings are refused.
             responses = ['', 'q', 'z']
-            humanfriendly.raw_input = lambda prompt: responses.pop(0)
+            humanfriendly.interactive_prompt = lambda prompt: responses.pop(0)
             self.assertEqual(humanfriendly.prompt_for_choice(['foo', 'bar', 'baz']), 'baz')
             # Choice selection by substring input requires an unambiguous substring match.
             responses = ['a', 'q']
-            humanfriendly.raw_input = lambda prompt: responses.pop(0)
+            humanfriendly.interactive_prompt = lambda prompt: responses.pop(0)
             self.assertEqual(humanfriendly.prompt_for_choice(['foo', 'bar', 'baz', 'qux']), 'qux')
             # Invalid numbers are refused.
             responses = ['42', '2']
-            humanfriendly.raw_input = lambda prompt: responses.pop(0)
+            humanfriendly.interactive_prompt = lambda prompt: responses.pop(0)
             self.assertEqual(humanfriendly.prompt_for_choice(['foo', 'bar', 'baz']), 'bar')
         finally:
-            humanfriendly.raw_input = raw_input
+            humanfriendly.interactive_prompt = interactive_prompt
 
 if __name__ == '__main__':
     unittest.main()