import all future features

Question

Just curious, I tried from __future__ import *, but I received this error:

  File "<stdin>", line 1
SyntaxError: future feature * is not defined

Well, that makes sense. A __future__ import is a little special and doesn't follow the normal rules, but it got me to thinking: how can I import all the future features?

Answer 1

You can't, and that's by design. This is because more __future__ features might be added in the future, and those can break your code.

Imagine that in 2.x, the only __future__ feature was division. Then in 2.y, a new __future__ feature, print_function, is introduced. All of a sudden my code has broken:

from __future__ import *
print "Hello, World!"

You can, however, import __future__, and inspect its contents:

>>> import __future__
>>> [x for x in dir(__future__) if x.islower() and x[0] != '_']
['absolute_import', 'all_feature_names', 'division', 'generator_stop', 'generators', 'nested_scopes', 'print_function', 'unicode_literals', 'with_statement']

Note that these are not features and you should not try to import them. They instead describe which features are available, and from which versions they are.