Python 3.4 import error

[neviaumi]

I have installed gflags on python3.4 env.
And after i attempt import gflags it raise "No module named 'cStringIO' "

It should by changed from io import StringIO

Possibly update look like below?

from

gflags/argument_parser.py 
import cStringIO
import csv
import string

to

gflags/argument_parser.py
try: 
     from io import StringIO as cStringIO
except:
     import cStringIO#original code here
import csv
import string

[nickjacobson]

This pull request: #22 contains code that would fix this issue, and other Python 3 compatibility issues.

[barabo]

I'm not sure that the above fix completely solves the problem with Python 3+

It does solve the import error, but I believe there are other issues with the argument_parser.CsvListSerializer class (like, unicode doesn't exist in python3 and it's mentioned within the Serialize function.)

class CsvListSerializer(ArgumentSerializer):

  def __init__(self, list_sep):
    self.list_sep = list_sep

  def Serialize(self, value):
    """Serialize a list as a string, if possible, or as a unicode string."""
    output = cStringIO.StringIO()
    writer = csv.writer(output)

    # csv.writer doesn't accept unicode, so we convert to UTF-8.
    encoded_value = [unicode(x).encode('utf-8') for x in value]  ### <- broken in python3
    writer.writerow(encoded_value)

Honestly, looking at the class right above this one - I'm not sure I understand why this wouldn't work instead for either major version of python:

CsvListSerializer = ListSerializer  # Alias class.

I say this because the CsvListSerializer already ignores the list_sep argument and the ListSerializer uses the _helpers.StrOrUnicode function (although, slightly differently) to convert the list values into unicode strings.

Unless I'm missing something, the CsvListSerializer class is basically useless and ListSerializer(',') could be used instead.

This would prevent the need to import cStringIO in this module entirely.

[crutcher]

Do we have any visibility on timelines here? Would additional work be welcome? I could work on py3 problems, but am unsure if they would be merged; some direction would be useful.

[gpshead]

It is actively being worked on internally, expect a push for Python 3 compatibility within a month is my best vague estimate (probably sooner but i'm not promising dates).

[sneakywombat]

@gpshead, anything we can do to help it along?

[gpshead]

We've got this working internally now; I expect @vrusinov will push the changes later this month.

[mrdrozdov]

@gpshead any followup on this?

[gpshead]

@vrusinov pushed an update and a 3.1.0 release earlier this month. give it a try.

[mrdrozdov]

This is so great! Thank you :)