requests源码分析（2） compat.py 处理py2和

# -*- coding: utf-8 -*-

"""
requests.compat
~~~~~~~~~~~~~~~

This module handles import compatibility issues between Python 2 and
Python 3.
"""

import chardet

import sys

# -------
# Pythons
# -------

# Syntax sugar.
# python版本   
# >>> print（sys.version_info）
#     sys.version_info(major=3, minor=6, micro=2, releaselevel='final', serial=0)

_ver = sys.version_info

#: Python 2.x?

is_py2 = (_ver[0] == 2)

#: Python 3.x?
is_py3 = (_ver[0] == 3)

# SimpleJSON 是一个 write-only 的实现，输出格式适合脚本语言解析
try:
    import simplejson as json
except ImportError:
    import json

# ---------
# Specifics
# ---------

if is_py2:
    from urllib import (
        quote, unquote, quote_plus, unquote_plus, urlencode, getproxies,
        proxy_bypass, proxy_bypass_environment, getproxies_environment)
    from urlparse import urlparse, urlunparse, urljoin, urlsplit, urldefrag
    from urllib2 import parse_http_list
    import cookielib
    from Cookie import Morsel
    from StringIO import StringIO

    from urllib3.packages.ordered_dict import OrderedDict

    builtin_str = str
    bytes = str
    str = unicode
    basestring = basestring
    numeric_types = (int, long, float)
    integer_types = (int, long)

elif is_py3:
    from urllib.parse import urlparse, urlunparse, urljoin, urlsplit, urlencode, quote, unquote, quote_plus, unquote_plus, urldefrag
    from urllib.request import parse_http_list, getproxies, proxy_bypass, proxy_bypass_environment, getproxies_environment
    from http import cookiejar as cookielib
    from http.cookies import Morsel
    from io import StringIO
    from collections import OrderedDict

    builtin_str = str
    str = str
    bytes = bytes
    basestring = (str, bytes)
    numeric_types = (int, float)
    integer_types = (int,)