Replace past with six (#134)

* Replace `past` with `six`
* Document issue with pycurl

Signed-off-by: Yuri Shkuro <[email protected]>

Author: yurishkuro

CONTRIBUTING.md

@@ -21,6 +21,21 @@ To install all dependencies, run:
  3. `make bootstrap`
  4. `make test`
 
+### pycurl
+
+On MacOS you may get an error:
+
+```
+ImportError: pycurl: libcurl link-time ssl backend (openssl) is different from compile-time ssl backend (none/other)
+```
+
+It can be fixed with:
+
+```
+pip uninstall pycurl
+pip install --install-option="--with-openssl" --install-option="--openssl-dir=/usr/local/opt/openssl" pycurl
+```
+
 ## Making A Change
 
 *Before making any significant changes, please [open an issue](https://github.com/jaegertracing/jaeger-client-python/issues).*

jaeger_client/codecs.py

@@ -15,7 +15,6 @@
 from __future__ import absolute_import
 
 from builtins import object
-from past.builtins import basestring
 
 from opentracing import (
     InvalidCarrierException,
@@ -164,7 +163,7 @@ def span_context_from_string(value):
             raise SpanContextCorruptedException(
                 'trace context must be a string or array of 1: "%s"' % value)
         value = value[0]
-    if not isinstance(value, basestring):
+    if not isinstance(value, six.string_types):
         raise SpanContextCorruptedException(
             'trace context not a string "%s"' % value)
     parts = value.split(':')

jaeger_client/thrift_gen/agent/Agent.py

@@ -4,7 +4,7 @@ BEGIN {six=0; xrange=0}
     # if in the future we need six, it can be added with the following line
     # if (six == 0) print "import six"
     six = 1
-    if (xrange ==0) print "from past.builtins import xrange"
+    if (xrange ==0) print "from six.moves import xrange"
     xrange = 1
 }