Python 3 dict behavior in Python 2

Question

I saw this question tonight. I had never heard of future_builtins before this, and it got me wondering. future_builtins only covers a few types, and

Answer 1

You can use viewkeys(), viewitems() and viewvalues() in py2x.

>>> dict.viewkeys?
Type:       method_descriptor
String Form:
Namespace:  Python builtin
Docstring:  D.viewkeys() -> a set-like object providing a view on D's keys

What’s New In Python 3.0 :

• dict methods dict.keys(), dict.items() and dict.values() return “views” instead of lists. For example, this no longer works: k = d.keys(); k.sort(). Use k = sorted(d) instead (this works in Python 2.5 too and is just as efficient).
• Also, the dict.iterkeys(), dict.iteritems() and dict.itervalues() methods are no longer supported.

Bug : Backport dictviews to 2.7:

After talking to Guido, got rid of the future import magic in favour of just providing viewkeys, viewitems and viewvalues methods of dicts. This makes efficient 2.6-and-3.0 dict-using code possibly by making 2to3 translate the view-methods directly to keys/values/items in 3.0, and not wrapping everything in list().

2to3 tool:

RefactoringTool: Refactored so.py
--- so.py   (original)
+++ so.py   (refactored)
@@ -1 +1 @@
-print dic.viewkeys()
+print(dic.keys())