Add support for Python 3

.travis.yml

@@ -11,6 +11,8 @@ cache:
 language: python
 python:
   - "2.7"
+  - "3.4"
+  - "3.5"
 install: pip install codecov tox-travis
 script: tox
 after_success:

google/gax/__init__.py

@@ -431,6 +431,10 @@ def __iter__(self):
         return self
 
     def next(self):
+        """For Python 2.7 compatibility; see __next__."""
+        return self.__next__()
+
+    def __next__(self):
         """Retrieves the next page."""
         if self._done:
             raise StopIteration
@@ -464,10 +468,14 @@ def __iter__(self):
         return self
 
     def next(self):
+        """For Python 2.7 compatibility; see __next__."""
+        return self.__next__()
+
+    def __next__(self):
         """Retrieves the next resource."""
         # pylint: disable=next-method-called
         while not self._current:
-            self._current = self._iterator.next()
+            self._current = next(self._iterator)
             self._index = 0
         resource = self._current[self._index]
         self._index += 1

google/gax/api_callable.py

@@ -31,9 +31,10 @@
 
 from __future__ import absolute_import, division
 import random
-import sys
 import time
 
+from future.utils import raise_with_traceback
+
 from . import (BackoffSettings, BundleOptions, bundling, CallSettings, config,
                PageIterator, ResourceIterator, RetryOptions)
 from .errors import GaxError, RetryError
@@ -429,8 +430,7 @@ def inner(*args, **kwargs):
             return a_func(*args, **kwargs)
         # pylint: disable=catching-non-exception
         except tuple(errors) as exception:
-            raise (GaxError('RPC failed', cause=exception), None,
-                   sys.exc_info()[2])
+            raise_with_traceback(GaxError('RPC failed', cause=exception))
 
     return inner
 

requirements.txt

@@ -1,3 +1,4 @@
+future>=0.15.2
 grpcio>=0.15.0
 oauth2client>=1.5.2
 ply==3.8

tox.ini

@@ -1,13 +1,14 @@
 [tox]
-envlist = py27,pep8,pylint-errors,pylint-full
+envlist = py27,py34,py35,pep8,pylint-errors,pylint-full
 
 [tox:travis]
-2.7 = py27, pep8, pylint-full, docs
+2.7 = py27,pep8,pylint-full,docs
+3.4 = py34,pep8,pylint-full
+3.5 = py35,pep8,pylint-full
 
 [testenv]
 setenv =
        PYTHONPATH = {toxinidir}:{toxinidir}/src-gen/test
-
 deps = -r{toxinidir}/test-requirements.txt
        -r{toxinidir}/requirements.txt
 whitelist_externals = mkdir
@@ -55,5 +56,6 @@ commands =
   sphinx-build -W -b html -d docs/_build/doctrees docs docs/_build/html
   sphinx-build -b latex -D language=en -d _build/doctrees docs _build/latex
 deps =
+  -r{toxinidir}/requirements.txt
   Sphinx
   sphinx_rtd_theme