NameError: global name 'unicode' is not defined - in Python 3

问题

I am trying to use a Python package called bidi. In a module in this package (algorithm.py) there are some lines that give me error, although it is part of the package.

Here are the lines:

# utf-8 ? we need unicode
if isinstance(unicode_or_str, unicode):
    text = unicode_or_str
    decoded = False
else:
    text = unicode_or_str.decode(encoding)
    decoded = True

and here is the error message:

Traceback (most recent call last):
  File \"<pyshell#25>\", line 1, in <module>
    bidi_text = get_display(reshaped_text)
  File \"C:\\Python33\\lib\\site-packages\\python_bidi-0.3.4-py3.3.egg\\bidi\\algorithm.py\",   line 602, in get_display
    if isinstance(unicode_or_str, unicode):
NameError: global name \'unicode\' is not defined

How should I re-write this part of the code so it works in Python3? Also if anyone have used bidi package with Python 3 please let me know if they have found similar problems or not. I appreciate your help.

回答1:

Python 3 renamed the unicode type to str, the old str type has been replaced by bytes.

if isinstance(unicode_or_str, str):
    text = unicode_or_str
    decoded = False
else:
    text = unicode_or_str.decode(encoding)
    decoded = True

You may want to read the Python 3 porting HOWTO for more such details. There is also Lennart Regebro's Porting to Python 3: An in-depth guide, free online.

Last but not least, you could just try to use the 2to3 tool to see how that translates the code for you.

回答2:

You can use the six library to support both Python 2 and 3:

import six
if isinstance(value, six.string_types):
    handle_string(value)

回答3:

If you need to have the script keep working on python2 and 3 as I did, this might help someone

import sys
if sys.version_info[0] >= 3:
    unicode = str

and can then just do for example

foo = unicode.lower(foo)

回答4:

Hope you are using Python 3 , Str are unicode by default, so please Replace Unicode function with String Str function.

if isinstance(unicode_or_str, str):    ##Replaces with str
    text = unicode_or_str
    decoded = False

来源：https://stackoverflow.com/questions/19877306/nameerror-global-name-unicode-is-not-defined-in-python-3