alex alex - 4 months ago 86
Python Question

Python 2.7: Print to File

Why does trying to print directly to a file instead of

sys.stdout
produce the following syntax error:

Python 2.7.2+ (default, Oct 4 2011, 20:06:09)
[GCC 4.6.1] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> f1=open('./testfile', 'w+')
>>> print('This is a test', file=f1)
File "<stdin>", line 1
print('This is a test', file=f1)
^
SyntaxError: invalid syntax


From help(__builtins__) I have the following info:

print(...)
print(value, ..., sep=' ', end='\n', file=sys.stdout)

Prints the values to a stream, or to sys.stdout by default.
Optional keyword arguments:
file: a file-like object (stream); defaults to the current sys.stdout.
sep: string inserted between values, default a space.
end: string appended after the last value, default a newline.


So what would be the right syntax to change the standard stream print writes to?

I know that there are different maybe better ways to write to file but I really don't get why this should be a syntax error...

A nice explanation would be appreciated!

Answer Source

If you want to use the print function in Python 2, you have to import from __future__:

from __future__ import print_function

But you can have the same effect without using the function, too:

print >>f1, 'This is a test'