为Python 2解压缩打印列表

Question

I'm having problem with understanding why unpacking does not work with list and print statement in Python 2.7:

>>> l=['a', 'b', 'c']
>>> print (*l, sep='')

Python 3.x works fine and prints:

abc

Python 2.7, however, raises an error:

 print (*l, sep='')
       ^
SyntaxError: invalid syntax

How can I make it work for Python 2.7?

I know I can alternatively code it using join with: ''.join(l)

Answer 1

Because print isn't a function in Python 2; unpacking a list and providing it as positional args isn't possible if it isn't a function .

You'll need to import the print_function from __future__ in order to support this:

>>> from __future__ import print_function

Now unpacking is possible:

>>> l = ['a', 'b', 'c']
>>> print(*l, sep='')
abc

Answer 2

You have two options:

• Convert to strings and join with spaces manually:

   print ''.join(map(str, l)) 

• Use the print() function , by using the from __future__ import that disables the print statement :

   from __future__ import print_function print(*l, sep='') 

  or directly call the function by accessing it via the __builtin__ module :

   import __builtin__ print_function = getattr(__builtin__, 'print') print_function(*l, sep='') 

  The same function is available in both Python 2 and 3, but in Python 2 you can't use it directly without first disabling keyword.