utils: add any value to iterable function

--HG--
extra : convert_revision : svn%3Ab85faa78-f9eb-468e-a121-7cced6da292c%40952

scrapy/trunk/scrapy/tests/test_utils_misc.py

@@ -1,7 +1,7 @@
 import unittest
 from cStringIO import StringIO
 
-from scrapy.utils.misc import hash_values, items_to_csv, load_object, arg_to_list
+from scrapy.utils.misc import hash_values, items_to_csv, load_object, arg_to_list, arg_to_iter
 from scrapy.item import ScrapedItem
 
 class UtilsMiscTestCase(unittest.TestCase):
@@ -67,5 +67,25 @@ class UtilsMiscTestCase(unittest.TestCase):
         self.assertEqual(arg_to_list(100), [100])
         self.assertEqual(arg_to_list(('lala', 'poo')), ['lala', 'poo'])
 
+    def test_arg_to_list(self):
+        self.assertEqual(arg_to_list(None), [])
+        self.assertEqual(arg_to_list('lala'), ['lala'])
+        self.assertEqual(arg_to_list(100), [100])
+        self.assertEqual(arg_to_list(('lala', 'poo')), ['lala', 'poo'])
+        self.assertEqual(arg_to_list(s for s in ['lala', 'poo']), ['lala', 'poo'])
+
+    def test_arg_to_iter(self):
+        assert hasattr(arg_to_iter(None), '__iter__')
+        assert hasattr(arg_to_iter(100), '__iter__')
+        assert hasattr(arg_to_iter('lala'), '__iter__')
+        assert hasattr(arg_to_iter([1,2,3]), '__iter__')
+        assert hasattr(arg_to_iter(l for l in 'abcd'), '__iter__')
+
+        self.assertEqual(list(arg_to_iter(None)), [])
+        self.assertEqual(list(arg_to_iter('lala')), ['lala'])
+        self.assertEqual(list(arg_to_iter(100)), [100])
+        self.assertEqual(list(arg_to_iter(l for l in 'abc')), ['a', 'b', 'c'])
+        self.assertEqual(list(arg_to_iter([1,2,3])), [1,2,3])
+
 if __name__ == "__main__":
     unittest.main()

scrapy/trunk/scrapy/utils/misc.py

@@ -16,8 +16,8 @@ from scrapy.utils.defer import defer_succeed
 
 def arg_to_list(arg):
     """Convert an argument to list, so that it can be iterated. The argument
-    can be a None, single value, or an iterable. 
-    
+    can be a None, single value, or an iterable.
+
     This is meant to be used in functions for arguments which can be either
     None, single valued or multi-valued.
     """
@@ -28,6 +28,17 @@ def arg_to_list(arg):
     else:
         return [arg]
 
+def arg_to_iter(arg):
+    """Convert an argument to an iterable. The argument can be a None, single
+    value, or an iterable.
+    """
+    if arg is None:
+        return []
+    elif hasattr(arg, '__iter__'):
+        return arg
+    else:
+        return [arg]
+
 def dict_updatedefault(D, E, **F):
     """
     updatedefault(D, E, **F) -> None.
@@ -101,7 +112,7 @@ load_class = load_object # backwards compatibility, but isnt going to be availab
 
 def extract_regex(regex, text, encoding):
     """Extract a list of unicode strings from the given text/encoding using the following policies:
-    
+
     * if the regex contains a named group called "extract" that will be returned
     * if the regex contains multiple numbered groups, all those will be returned (flattened)
     * if the regex doesn't contain any group the entire regex matching is returned
@@ -122,8 +133,8 @@ def extract_regex(regex, text, encoding):
         return [remove_entities(unicode(s, encoding), keep=['lt', 'amp']) for s in strings]
 
 def hash_values(*values):
-    """Hash a series of non-None values. 
-    
+    """Hash a series of non-None values.
+
     For example:
     >>> hash_values('some', 'values', 'to', 'hash')
     'f37f5dc65beaaea35af05e16e26d439fd150c576'