--- a/dataimport/csv.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/dataimport/csv.py	Mon Sep 14 16:03:07 2015 +0200
@@ -22,11 +22,13 @@
 import warnings
 import os.path as osp
 
+from six import string_types
+
 from logilab.common import shellutils
 
 
 def count_lines(stream_or_filename):
-    if isinstance(stream_or_filename, basestring):
+    if isinstance(stream_or_filename, string_types):
         f = open(stream_or_filename)
     else:
         f = stream_or_filename
@@ -47,7 +49,7 @@
     if quote is not None:
         quotechar = quote
         warnings.warn("[3.20] 'quote' kwarg is deprecated, use 'quotechar' instead")
-    if isinstance(stream_or_path, basestring):
+    if isinstance(stream_or_path, string_types):
         if not osp.exists(stream_or_path):
             raise Exception("file doesn't exists: %s" % stream_or_path)
         stream = open(stream_or_path)

--- a/dataimport/pgstore.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/dataimport/pgstore.py	Mon Sep 14 16:03:07 2015 +0200
@@ -27,6 +27,7 @@
 from collections import defaultdict
 from base64 import b64encode
 
+from six import string_types
 from six.moves import cPickle as pickle, range
 
 from cubicweb.utils import make_uid
@@ -166,7 +167,7 @@
 _COPYFROM_BUFFER_CONVERTERS = [
     (type(None), _copyfrom_buffer_convert_None),
     ((long, int, float), _copyfrom_buffer_convert_number),
-    (basestring, _copyfrom_buffer_convert_string),
+    (string_types, _copyfrom_buffer_convert_string),
     (datetime, _copyfrom_buffer_convert_datetime),
     (date, _copyfrom_buffer_convert_date),
     (time, _copyfrom_buffer_convert_time),

--- a/devtools/fake.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/devtools/fake.py	Mon Sep 14 16:03:07 2015 +0200
@@ -22,6 +22,8 @@
 
 from contextlib import contextmanager
 
+from six import string_types
+
 from logilab.database import get_db_helper
 
 from cubicweb.req import RequestSessionBase
@@ -91,7 +93,7 @@
 
     def set_request_header(self, header, value, raw=False):
         """set an incoming HTTP header (for test purpose only)"""
-        if isinstance(value, basestring):
+        if isinstance(value, string_types):
             value = [value]
         if raw:
             # adding encoded header is important, else page content

--- a/devtools/testlib.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/devtools/testlib.py	Mon Sep 14 16:03:07 2015 +0200
@@ -28,6 +28,7 @@
 from warnings import warn
 from itertools import chain
 
+from six import string_types
 from six.moves import range
 from six.moves.urllib.parse import urlparse, parse_qs, unquote as urlunquote
 
@@ -521,7 +522,7 @@
         """
         torestore = []
         for erschema, etypeperms in chain(perm_overrides, perm_kwoverrides.iteritems()):
-            if isinstance(erschema, basestring):
+            if isinstance(erschema, string_types):
                 erschema = self.schema[erschema]
             for action, actionperms in etypeperms.iteritems():
                 origperms = erschema.permissions[action]

--- a/entities/__init__.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/entities/__init__.py	Mon Sep 14 16:03:07 2015 +0200
@@ -19,6 +19,7 @@
 
 __docformat__ = "restructuredtext en"
 
+from six import string_types
 
 from logilab.common.decorators import classproperty
 
@@ -134,7 +135,7 @@
             return self.dc_title().lower()
         value = self.cw_attr_value(rtype)
         # do not restrict to `unicode` because Bytes will return a `str` value
-        if isinstance(value, basestring):
+        if isinstance(value, string_types):
             return self.printable_value(rtype, format='text/plain').lower()
         return value
 

--- a/entities/authobjs.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/entities/authobjs.py	Mon Sep 14 16:03:07 2015 +0200
@@ -19,6 +19,8 @@
 
 __docformat__ = "restructuredtext en"
 
+from six import string_types
+
 from logilab.common.decorators import cached
 
 from cubicweb import Unauthorized
@@ -126,7 +128,7 @@
         :type groups: str or iterable(str)
         :param groups: a group name or an iterable on group names
         """
-        if isinstance(groups, basestring):
+        if isinstance(groups, string_types):
             groups = frozenset((groups,))
         elif isinstance(groups, (tuple, list)):
             groups = frozenset(groups)

--- a/entities/wfobjs.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/entities/wfobjs.py	Mon Sep 14 16:03:07 2015 +0200
@@ -25,6 +25,7 @@
 
 __docformat__ = "restructuredtext en"
 
+from six import string_types
 
 from logilab.common.decorators import cached, clear_cache
 from logilab.common.deprecation import deprecated
@@ -259,10 +260,10 @@
                                     'WHERE T eid %(x)s, G name %(gn)s',
                                     {'x': self.eid, 'gn': unicode(gname)})
             assert rset, '%s is not a known group' % gname
-        if isinstance(conditions, basestring):
+        if isinstance(conditions, string_types):
             conditions = (conditions,)
         for expr in conditions:
-            if isinstance(expr, basestring):
+            if isinstance(expr, string_types):
                 kwargs = {'expr': unicode(expr)}
             else:
                 assert isinstance(expr, dict)
@@ -529,7 +530,7 @@
 
     def _get_transition(self, tr):
         assert self.current_workflow
-        if isinstance(tr, basestring):
+        if isinstance(tr, string_types):
             _tr = self.current_workflow.transition_by_name(tr)
             assert _tr is not None, 'not a %s transition: %s' % (
                 self.__regid__, tr)

--- a/entity.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/entity.py	Mon Sep 14 16:03:07 2015 +0200
@@ -22,6 +22,7 @@
 from warnings import warn
 from functools import partial
 
+from six import string_types
 from six.moves import range
 
 from logilab.common.decorators import cached
@@ -281,7 +282,7 @@
             select = Select()
             mainvar = select.get_variable(mainvar)
             select.add_selected(mainvar)
-        elif isinstance(mainvar, basestring):
+        elif isinstance(mainvar, string_types):
             assert mainvar in select.defined_vars
             mainvar = select.get_variable(mainvar)
         # eases string -> syntax tree test transition: please remove once stable
@@ -697,7 +698,7 @@
         attr = str(attr)
         if value is _marker:
             value = getattr(self, attr)
-        if isinstance(value, basestring):
+        if isinstance(value, string_types):
             value = value.strip()
         if value is None or value == '': # don't use "not", 0 is an acceptable value
             return u''

--- a/migration.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/migration.py	Mon Sep 14 16:03:07 2015 +0200
@@ -27,6 +27,8 @@
 from os.path import exists, join, basename, splitext
 from itertools import chain
 
+from six import string_types
+
 from logilab.common import IGNORED_EXTENSIONS
 from logilab.common.decorators import cached
 from logilab.common.configuration import REQUIRED, read_old_config
@@ -397,7 +399,7 @@
         """modify the list of used cubes in the in-memory config
         returns newly inserted cubes, including dependencies
         """
-        if isinstance(cubes, basestring):
+        if isinstance(cubes, string_types):
             cubes = (cubes,)
         origcubes = self.config.cubes()
         newcubes = [p for p in self.config.expand_cubes(cubes)

--- a/predicates.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/predicates.py	Mon Sep 14 16:03:07 2015 +0200
@@ -24,6 +24,7 @@
 from warnings import warn
 from operator import eq
 
+from six import string_types
 from six.moves import range
 
 from logilab.common.deprecation import deprecated
@@ -613,7 +614,7 @@
         super(is_instance, self).__init__(**kwargs)
         self.expected_etypes = expected_etypes
         for etype in self.expected_etypes:
-            assert isinstance(etype, basestring), etype
+            assert isinstance(etype, string_types), etype
 
     def __str__(self):
         return '%s(%s)' % (self.__class__.__name__,
@@ -1093,7 +1094,7 @@
     """
     if from_state_name is not None:
         warn("on_fire_transition's from_state_name argument is unused", DeprecationWarning)
-    if isinstance(tr_names, basestring):
+    if isinstance(tr_names, string_types):
         tr_names = set((tr_names,))
     def match_etype_and_transition(trinfo):
         # take care trinfo.transition is None when calling change_state
@@ -1293,7 +1294,7 @@
             raise ValueError("match_form_params() can't be called with both "
                              "positional and named arguments")
         if expected:
-            if len(expected) == 1 and not isinstance(expected[0], basestring):
+            if len(expected) == 1 and not isinstance(expected[0], string_types):
                 raise ValueError("match_form_params() positional arguments "
                                  "must be strings")
             super(match_form_params, self).__init__(*expected)

--- a/rqlrewrite.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/rqlrewrite.py	Mon Sep 14 16:03:07 2015 +0200
@@ -22,6 +22,8 @@
 """
 __docformat__ = "restructuredtext en"
 
+from six import string_types
+
 from rql import nodes as n, stmts, TypeResolverException
 from rql.utils import common_parent
 
@@ -883,7 +885,7 @@
                 return n.Constant(vi['const'], 'Int')
             return n.VariableRef(stmt.get_variable(selectvar))
         vname_or_term = self._get_varname_or_term(node.name)
-        if isinstance(vname_or_term, basestring):
+        if isinstance(vname_or_term, string_types):
             return n.VariableRef(stmt.get_variable(vname_or_term))
         # shared term
         return vname_or_term.copy(stmt)

--- a/rtags.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/rtags.py	Mon Sep 14 16:03:07 2015 +0200
@@ -40,6 +40,8 @@
 import logging
 from warnings import warn
 
+from six import string_types
+
 from logilab.common.logging_ext import set_log_methods
 from logilab.common.registry import RegistrableInstance, yes
 
@@ -145,7 +147,7 @@
         return tag
 
     def _tag_etype_attr(self, etype, attr, desttype='*', *args, **kwargs):
-        if isinstance(attr, basestring):
+        if isinstance(attr, string_types):
             attr, role = attr, 'subject'
         else:
             attr, role = attr

--- a/schema.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/schema.py	Mon Sep 14 16:03:07 2015 +0200
@@ -26,6 +26,7 @@
 from logging import getLogger
 from warnings import warn
 
+from six import string_types
 from six.moves import range
 
 from logilab.common import tempattr
@@ -207,7 +208,7 @@
         """
         self.eid = eid # eid of the entity representing this rql expression
         assert mainvars, 'bad mainvars %s' % mainvars
-        if isinstance(mainvars, basestring):
+        if isinstance(mainvars, string_types):
             mainvars = set(splitstrip(mainvars))
         elif not isinstance(mainvars, set):
             mainvars = set(mainvars)
@@ -579,7 +580,7 @@
     assert action in self.ACTIONS, action
     #assert action in self._groups, '%s %s' % (self, action)
     try:
-        return frozenset(g for g in self.permissions[action] if isinstance(g, basestring))
+        return frozenset(g for g in self.permissions[action] if isinstance(g, string_types))
     except KeyError:
         return ()
 PermissionMixIn.get_groups = get_groups
@@ -598,7 +599,7 @@
     assert action in self.ACTIONS, action
     #assert action in self._rqlexprs, '%s %s' % (self, action)
     try:
-        return tuple(g for g in self.permissions[action] if not isinstance(g, basestring))
+        return tuple(g for g in self.permissions[action] if not isinstance(g, string_types))
     except KeyError:
         return ()
 PermissionMixIn.get_rqlexprs = get_rqlexprs

--- a/selectors.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/selectors.py	Mon Sep 14 16:03:07 2015 +0200
@@ -18,6 +18,8 @@
 
 from warnings import warn
 
+from six import string_types
+
 from logilab.common.deprecation import deprecated, class_renamed
 
 from cubicweb.predicates import *
@@ -84,7 +86,7 @@
 
     See `EntityPredicate` documentation for behaviour when row is not specified.
 
-    :param *etypes: entity types (`basestring`) which should be refused
+    :param *etypes: entity types (`string_types`) which should be refused
     """
     def __init__(self, *etypes):
         super(_but_etype, self).__init__()

--- a/server/__init__.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/server/__init__.py	Mon Sep 14 16:03:07 2015 +0200
@@ -29,6 +29,8 @@
 from glob import glob
 from contextlib import contextmanager
 
+from six import string_types
+
 from logilab.common.modutils import LazyObject
 from logilab.common.textutils import splitstrip
 from logilab.common.registry import yes
@@ -139,7 +141,7 @@
     if not debugmode:
         DEBUG = 0
         return
-    if isinstance(debugmode, basestring):
+    if isinstance(debugmode, string_types):
         for mode in splitstrip(debugmode, sep='|'):
             DEBUG |= globals()[mode]
     else:

--- a/server/querier.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/server/querier.py	Mon Sep 14 16:03:07 2015 +0200
@@ -24,6 +24,7 @@
 
 from itertools import repeat
 
+from six import string_types
 from six.moves import range
 
 from rql import RQLSyntaxError, CoercionError
@@ -450,11 +451,11 @@
         relations = {}
         for subj, rtype, obj in self.relation_defs():
             # if a string is given into args instead of an int, we get it here
-            if isinstance(subj, basestring):
+            if isinstance(subj, string_types):
                 subj = int(subj)
             elif not isinstance(subj, (int, long)):
                 subj = subj.entity.eid
-            if isinstance(obj, basestring):
+            if isinstance(obj, string_types):
                 obj = int(obj)
             elif not isinstance(obj, (int, long)):
                 obj = obj.entity.eid

--- a/server/schemaserial.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/server/schemaserial.py	Mon Sep 14 16:03:07 2015 +0200
@@ -24,6 +24,8 @@
 import json
 import sys
 
+from six import string_types
+
 from logilab.common.shellutils import ProgressBar, DummyProgressBar
 
 from yams import BadSchemaDefinition, schema as schemamod, buildobjs as ybo
@@ -614,7 +616,7 @@
             # may occurs when modifying persistent schema
             continue
         for group_or_rqlexpr in grantedto:
-            if isinstance(group_or_rqlexpr, basestring):
+            if isinstance(group_or_rqlexpr, string_types):
                 # group
                 try:
                     yield ('SET X %s_permission Y WHERE Y eid %%(g)s, X eid %%(x)s' % action,

--- a/server/serverctl.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/server/serverctl.py	Mon Sep 14 16:03:07 2015 +0200
@@ -29,6 +29,8 @@
 import logging
 import subprocess
 
+from six import string_types
+
 from logilab.common import nullobject
 from logilab.common.configuration import Configuration, merge_options
 from logilab.common.shellutils import ASK, generate_password
@@ -1020,7 +1022,7 @@
     for p in ('read', 'add', 'update', 'delete'):
         rule = perms.get(p)
         if rule:
-            perms[p] = tuple(str(x) if isinstance(x, basestring) else x
+            perms[p] = tuple(str(x) if isinstance(x, string_types) else x
                              for x in rule)
     return perms, perms in defaultrelperms or perms in defaulteperms
 

--- a/server/sources/ldapfeed.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/server/sources/ldapfeed.py	Mon Sep 14 16:03:07 2015 +0200
@@ -21,6 +21,8 @@
 
 from datetime import datetime
 
+from six import string_types
+
 import ldap
 from ldap.ldapobject import ReconnectLDAPObject
 from ldap.filter import filter_format
@@ -376,7 +378,7 @@
                     itemdict[key] = value
         # we expect memberUid to be a list of user ids, make sure of it
         member = self.group_rev_attrs['member']
-        if isinstance(itemdict.get(member), basestring):
+        if isinstance(itemdict.get(member), string_types):
             itemdict[member] = [itemdict[member]]
         return itemdict
 

--- a/server/sources/native.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/server/sources/native.py	Mon Sep 14 16:03:07 2015 +0200
@@ -38,6 +38,7 @@
 import logging
 import sys
 
+from six import string_types
 from six.moves import range, cPickle as pickle
 
 from logilab.common.decorators import cached, clear_cache
@@ -558,7 +559,7 @@
                 sql, qargs, cbs = self._rql_sqlgen.generate(union, args, varmap)
                 self._cache[cachekey] = sql, qargs, cbs
         args = self.merge_args(args, qargs)
-        assert isinstance(sql, basestring), repr(sql)
+        assert isinstance(sql, string_types), repr(sql)
         cursor = self.doexec(cnx, sql, args)
         results = self.process_result(cursor, cnx, cbs)
         assert dbg_results(results)

--- a/server/sqlutils.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/server/sqlutils.py	Mon Sep 14 16:03:07 2015 +0200
@@ -27,6 +27,7 @@
 from os.path import abspath
 from logging import getLogger
 
+from six import string_types
 from six.moves import filter
 
 from logilab import database as db, common as lgc
@@ -70,7 +71,7 @@
     else:
         execute = cursor_or_execute
     sqlstmts_as_string = False
-    if isinstance(sqlstmts, basestring):
+    if isinstance(sqlstmts, string_types):
         sqlstmts_as_string = True
         sqlstmts = sqlstmts.split(delimiter)
     if withpb:

--- a/server/test/unittest_ldapsource.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/server/test/unittest_ldapsource.py	Mon Sep 14 16:03:07 2015 +0200
@@ -26,6 +26,7 @@
 import subprocess
 import tempfile
 
+from six import string_types
 from six.moves import range
 
 from logilab.common.testlib import TestCase, unittest_main, mock_object, Tags
@@ -155,7 +156,7 @@
         """
         modcmd = ['dn: %s'%dn, 'changetype: add']
         for key, values in mods.iteritems():
-            if isinstance(values, basestring):
+            if isinstance(values, string_types):
                 values = [values]
             for value in values:
                 modcmd.append('%s: %s'%(key, value))
@@ -175,7 +176,7 @@
         modcmd = ['dn: %s'%dn, 'changetype: modify']
         for (kind, key), values in mods.iteritems():
             modcmd.append('%s: %s' % (kind, key))
-            if isinstance(values, basestring):
+            if isinstance(values, string_types):
                 values = [values]
             for value in values:
                 modcmd.append('%s: %s'%(key, value))

--- a/test/unittest_rqlrewrite.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/test/unittest_rqlrewrite.py	Mon Sep 14 16:03:07 2015 +0200
@@ -16,6 +16,8 @@
 # You should have received a copy of the GNU Lesser General Public License along
 # with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.
 
+from six import string_types
+
 from logilab.common.testlib import unittest_main, TestCase
 from logilab.common.testlib import mock_object
 from yams import BadSchemaDefinition
@@ -67,7 +69,7 @@
     rewriter = _prepare_rewriter(rqlrewrite.RQLRewriter, kwargs)
     snippets = []
     for v, exprs in sorted(snippets_map.items()):
-        rqlexprs = [isinstance(snippet, basestring)
+        rqlexprs = [isinstance(snippet, string_types)
                     and mock_object(snippet_rqlst=parse('Any X WHERE '+snippet).children[0],
                                     expression='Any X WHERE '+snippet)
                     or snippet

--- a/test/unittest_rset.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/test/unittest_rset.py	Mon Sep 14 16:03:07 2015 +0200
@@ -18,6 +18,7 @@
 # with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.
 """unit tests for module cubicweb.utils"""
 
+from six import string_types
 from six.moves import cPickle as pickle
 from six.moves.urllib.parse import urlsplit
 
@@ -552,17 +553,17 @@
     def test_str(self):
         with self.admin_access.web_request() as req:
             rset = req.execute('(Any X,N WHERE X is CWGroup, X name N)')
-            self.assertIsInstance(str(rset), basestring)
+            self.assertIsInstance(str(rset), string_types)
             self.assertEqual(len(str(rset).splitlines()), 1)
 
     def test_repr(self):
         with self.admin_access.web_request() as req:
             rset = req.execute('(Any X,N WHERE X is CWGroup, X name N)')
-            self.assertIsInstance(repr(rset), basestring)
+            self.assertIsInstance(repr(rset), string_types)
             self.assertTrue(len(repr(rset).splitlines()) > 1)
 
             rset = req.execute('(Any X WHERE X is CWGroup, X name "managers")')
-            self.assertIsInstance(str(rset), basestring)
+            self.assertIsInstance(str(rset), string_types)
             self.assertEqual(len(str(rset).splitlines()), 1)
 
     def test_nonregr_symmetric_relation(self):

--- a/uilib.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/uilib.py	Mon Sep 14 16:03:07 2015 +0200
@@ -28,6 +28,8 @@
 import re
 from StringIO import StringIO
 
+from six import string_types
+
 from logilab.mtconverter import xml_escape, html_unescape
 from logilab.common.date import ustrftime
 from logilab.common.deprecation import deprecated
@@ -559,7 +561,7 @@
     def __call__(self, function):
         def newfunc(*args, **kwargs):
             ret = function(*args, **kwargs)
-            if isinstance(ret, basestring):
+            if isinstance(ret, string_types):
                 return ret[:self.maxsize]
             return ret
         return newfunc
@@ -568,6 +570,6 @@
 def htmlescape(function):
     def newfunc(*args, **kwargs):
         ret = function(*args, **kwargs)
-        assert isinstance(ret, basestring)
+        assert isinstance(ret, string_types)
         return xml_escape(ret)
     return newfunc

--- a/web/facet.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/web/facet.py	Mon Sep 14 16:03:07 2015 +0200
@@ -57,6 +57,8 @@
 from copy import deepcopy
 from datetime import datetime, timedelta
 
+from six import string_types
+
 from logilab.mtconverter import xml_escape
 from logilab.common.graph import has_path
 from logilab.common.decorators import cached, cachedproperty
@@ -754,7 +756,7 @@
         # XXX handle rel is None case in RQLPathFacet?
         if self.restr_attr != 'eid':
             self.select.set_distinct(True)
-        if isinstance(value, basestring):
+        if isinstance(value, string_types):
             # only one value selected
             if value:
                 self.select.add_constant_restriction(
@@ -1071,7 +1073,7 @@
         assert self.path and isinstance(self.path, (list, tuple)), \
             'path should be a list of 3-uples, not %s' % self.path
         for part in self.path:
-            if isinstance(part, basestring):
+            if isinstance(part, string_types):
                 part = part.split()
             assert len(part) == 3, \
                    'path should be a list of 3-uples, not %s' % part
@@ -1147,7 +1149,7 @@
         varmap = {'X': self.filtered_variable}
         actual_filter_variable = None
         for part in self.path:
-            if isinstance(part, basestring):
+            if isinstance(part, string_types):
                 part = part.split()
             subject, rtype, object = part
             if skiplabel and object == self.label_variable:
@@ -1390,7 +1392,7 @@
             skiplabel=True, skipattrfilter=True)
         restrel = None
         for part in self.path:
-            if isinstance(part, basestring):
+            if isinstance(part, string_types):
                 part = part.split()
             subject, rtype, object = part
             if object == self.filter_variable:

--- a/web/formfields.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/web/formfields.py	Mon Sep 14 16:03:07 2015 +0200
@@ -66,6 +66,8 @@
 from warnings import warn
 from datetime import datetime, timedelta
 
+from six import string_types
+
 from logilab.mtconverter import xml_escape
 from logilab.common import nullobject
 from logilab.common.date import ustrftime
@@ -842,7 +844,7 @@
             self.widget.attrs.setdefault('size', self.default_text_input_size)
 
     def _ensure_correctly_typed(self, form, value):
-        if isinstance(value, basestring):
+        if isinstance(value, string_types):
             value = value.strip()
             if not value:
                 return None
@@ -924,7 +926,7 @@
         return self.format_single_value(req, 1.234)
 
     def _ensure_correctly_typed(self, form, value):
-        if isinstance(value, basestring):
+        if isinstance(value, string_types):
             value = value.strip()
             if not value:
                 return None
@@ -956,7 +958,7 @@
         return u'20s, 10min, 24h, 4d'
 
     def _ensure_correctly_typed(self, form, value):
-        if isinstance(value, basestring):
+        if isinstance(value, string_types):
             value = value.strip()
             if not value:
                 return None
@@ -986,7 +988,7 @@
         return self.format_single_value(req, datetime.now())
 
     def _ensure_correctly_typed(self, form, value):
-        if isinstance(value, basestring):
+        if isinstance(value, string_types):
             value = value.strip()
             if not value:
                 return None

--- a/web/formwidgets.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/web/formwidgets.py	Mon Sep 14 16:03:07 2015 +0200
@@ -99,6 +99,8 @@
 from datetime import date
 from warnings import warn
 
+from six import string_types
+
 from logilab.mtconverter import xml_escape
 from logilab.common.deprecation import deprecated
 from logilab.common.date import todatetime
@@ -282,7 +284,7 @@
         """
         posted = form._cw.form
         val = posted.get(field.input_name(form, self.suffix))
-        if isinstance(val, basestring):
+        if isinstance(val, string_types):
             val = val.strip()
         return val
 
@@ -993,12 +995,12 @@
         req = form._cw
         values = {}
         path = req.form.get(field.input_name(form, 'path'))
-        if isinstance(path, basestring):
+        if isinstance(path, string_types):
             path = path.strip()
         if path is None:
             path = u''
         fqs = req.form.get(field.input_name(form, 'fqs'))
-        if isinstance(fqs, basestring):
+        if isinstance(fqs, string_types):
             fqs = fqs.strip() or None
             if fqs:
                 for i, line in enumerate(fqs.split('\n')):

--- a/web/http_headers.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/web/http_headers.py	Mon Sep 14 16:03:07 2015 +0200
@@ -7,6 +7,7 @@
 import base64
 import re
 
+from six import string_types
 from six.moves.urllib.parse import urlparse
 
 
@@ -382,7 +383,7 @@
 
 def unique(seq):
     '''if seq is not a string, check it's a sequence of one element and return it'''
-    if isinstance(seq, basestring):
+    if isinstance(seq, string_types):
         return seq
     if len(seq) != 1:
         raise ValueError('single value required, not %s' % seq)
@@ -454,10 +455,10 @@
 
     """
     if (value in (True, 1) or
-            isinstance(value, basestring) and value.lower() == 'true'):
+            isinstance(value, string_types) and value.lower() == 'true'):
         return 'true'
     if (value in (False, 0) or
-            isinstance(value, basestring) and value.lower() == 'false'):
+            isinstance(value, string_types) and value.lower() == 'false'):
         return 'false'
     raise ValueError("Invalid true/false header value: %s" % value)
 

--- a/web/request.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/web/request.py	Mon Sep 14 16:03:07 2015 +0200
@@ -28,6 +28,7 @@
 from datetime import date, datetime
 from warnings import warn
 
+from six import string_types
 from six.moves import http_client
 from six.moves.urllib.parse import urlsplit, quote as urlquote
 from six.moves.http_cookies import SimpleCookie
@@ -437,7 +438,7 @@
             eids = form['eid']
         except KeyError:
             raise NothingToEdit(self._('no selected entities'))
-        if isinstance(eids, basestring):
+        if isinstance(eids, string_types):
             eids = (eids,)
         for peid in eids:
             if withtype:
@@ -596,7 +597,7 @@
         :param localfile: if True, the default data dir prefix is added to the
                           JS filename
         """
-        if isinstance(jsfiles, basestring):
+        if isinstance(jsfiles, string_types):
             jsfiles = (jsfiles,)
         for jsfile in jsfiles:
             if localfile:
@@ -616,7 +617,7 @@
                        the css inclusion. cf:
                        http://msdn.microsoft.com/en-us/library/ms537512(VS.85).aspx
         """
-        if isinstance(cssfiles, basestring):
+        if isinstance(cssfiles, string_types):
             cssfiles = (cssfiles,)
         if ieonly:
             if self.ie_browser():

--- a/web/schemaviewer.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/web/schemaviewer.py	Mon Sep 14 16:03:07 2015 +0200
@@ -20,6 +20,8 @@
 __docformat__ = "restructuredtext en"
 _ = unicode
 
+from six import string_types
+
 from logilab.common.ureports import Section, Title, Table, Link, Span, Text
 
 from yams.schema2dot import CARD_MAP
@@ -226,7 +228,7 @@
                     elif isinstance(val, (list, tuple)):
                         val = sorted(val)
                         val = ', '.join(str(v) for v in val)
-                    elif val and isinstance(val, basestring):
+                    elif val and isinstance(val, string_types):
                         val = _(val)
                     else:
                         val = str(val)

--- a/web/views/tableview.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/web/views/tableview.py	Mon Sep 14 16:03:07 2015 +0200
@@ -67,6 +67,7 @@
 from copy import copy
 from types import MethodType
 
+from six import string_types
 from six.moves import range
 
 from logilab.mtconverter import xml_escape
@@ -286,7 +287,7 @@
         attrs = renderer.attributes.copy()
         if renderer.sortable:
             sortvalue = renderer.sortvalue(rownum)
-            if isinstance(sortvalue, basestring):
+            if isinstance(sortvalue, string_types):
                 sortvalue = sortvalue[:self.sortvalue_limit]
             if sortvalue is not None:
                 attrs[u'cubicweb:sortvalue'] = js_dumps(sortvalue)

--- a/web/views/tabs.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/web/views/tabs.py	Mon Sep 14 16:03:07 2015 +0200
@@ -20,6 +20,8 @@
 __docformat__ = "restructuredtext en"
 _ = unicode
 
+from six import string_types
+
 from logilab.common.deprecation import class_renamed
 from logilab.mtconverter import xml_escape
 
@@ -114,7 +116,7 @@
         active_tab = uilib.domid(default_tab)
         viewsvreg = self._cw.vreg['views']
         for tab in tabs:
-            if isinstance(tab, basestring):
+            if isinstance(tab, string_types):
                 tabid, tabkwargs = tab, {}
             else:
                 tabid, tabkwargs = tab

--- a/web/views/uicfg.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/web/views/uicfg.py	Mon Sep 14 16:03:07 2015 +0200
@@ -57,6 +57,8 @@
 
 from warnings import warn
 
+from six import string_types
+
 from cubicweb import neg_role
 from cubicweb.rtags import (RelationTags, RelationTagsBool, RelationTagsSet,
                             RelationTagsDict, NoTargetRelationTagsDict,
@@ -650,7 +652,7 @@
                 self.tag_relation((sschema, rschema, oschema, role), True)
 
     def _tag_etype_attr(self, etype, attr, desttype='*', *args, **kwargs):
-        if isinstance(attr, basestring):
+        if isinstance(attr, string_types):
             attr, role = attr, 'subject'
         else:
             attr, role = attr

--- a/web/views/urlrewrite.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/web/views/urlrewrite.py	Mon Sep 14 16:03:07 2015 +0200
@@ -19,6 +19,8 @@
 
 import re
 
+from six import string_types
+
 from cubicweb.uilib import domid
 from cubicweb.appobject import AppObject
 
@@ -122,14 +124,14 @@
                 required_groups = None
             if required_groups and not req.user.matching_groups(required_groups):
                 continue
-            if isinstance(inputurl, basestring):
+            if isinstance(inputurl, string_types):
                 if inputurl == uri:
                     req.form.update(infos)
                     break
             elif inputurl.match(uri): # it's a regexp
                 # XXX what about i18n? (vtitle for instance)
                 for param, value in infos.items():
-                    if isinstance(value, basestring):
+                    if isinstance(value, string_types):
                         req.form[param] = inputurl.sub(value, uri)
                     else:
                         req.form[param] = value
@@ -222,7 +224,7 @@
                 required_groups = None
             if required_groups and not req.user.matching_groups(required_groups):
                 continue
-            if isinstance(inputurl, basestring):
+            if isinstance(inputurl, string_types):
                 if inputurl == uri:
                     return callback(inputurl, uri, req, self._cw.vreg.schema)
             elif inputurl.match(uri): # it's a regexp