python – Why does using from __future__ import print_function breaks Python2-style print?
First of all,
from __future__ import print_function needs to be the first line of code in your script (aside from some exceptions mentioned below). Second of all, as other answers have said, you have to use
from __future__ import print_function; to bring the
from __future__ import print_function import sys, os, time for x in range(0,10): print(x, sep= , end=) # No need for sep here, but okay :) time.sleep(1)
__future__ statements need to be near the top of the file because they change fundamental things about the language, and so the compiler needs to know about them from the beginning. From the documentation:
A future statement is recognized and treated specially at compile
time: Changes to the semantics of core constructs are often
implemented by generating different code. It may even be the case that
a new feature introduces new incompatible syntax (such as a new
reserved word), in which case the compiler may need to parse the
module differently. Such decisions cannot be pushed off until runtime.
The documentation also mentions that the only things that can precede a
__future__ statement are the module docstring, comments, blank lines, and other future statements.