[FIXED] Getting SyntaxError for print with keyword argument end=' '

Issue

When I try this code:

if Verbose:
   print("Building internam Index for %d tile(s) ..." % len(inputTiles), end=' ')

I get a SyntaxError claiming that end=' ' is invalid syntax.

Why does this happen?

---

_{See What does "SyntaxError: Missing parentheses in call to 'print'" mean in Python? for the opposite problem.}

_{See Why is parenthesis in print voluntary in Python 2.7? for general consequences of Python 2's treatment of print as a statement.}

Solution

Are you sure you are using Python 3.x? The syntax isn't available in Python 2.x because print is still a statement.

print("foo" % bar, end=" ")

in Python 2.x is identical to

print ("foo" % bar, end=" ")

or

print "foo" % bar, end=" "

i.e. as a call to print with a tuple as argument.

That's obviously bad syntax (literals don't take keyword arguments). In Python 3.x print is an actual function, so it takes keyword arguments, too.

The correct idiom in Python 2.x for end=" " is:

print "foo" % bar,

(note the final comma, this makes it end the line with a space rather than a linebreak)

If you want more control over the output, consider using sys.stdout directly. This won't do any special magic with the output.

Of course in somewhat recent versions of Python 2.x (2.5 should have it, not sure about 2.4), you can use the __future__ module to enable it in your script file:

from __future__ import print_function

The same goes with unicode_literals and some other nice things (with_statement, for example). This won't work in really old versions (i.e. created before the feature was introduced) of Python 2.x, though.

Answered By - Alan Plum