python兼容性问题

1. 获取python版本

PY_VERSION = sys.version_info[:3]
PY2 = PY_VERSION[0] == 2
PY3 = not PY2

2. 定义python不同版本的处理

if PY2:
    # io.StringIO only accepts u'foo' with Python 2.
    from StringIO import StringIO


    def py2to3(cls):
        if hasattr(cls, '__unicode__'):
            cls.__str__ = lambda self: unicode(self).encode('UTF-8')
        return cls

else:
    from io import StringIO


    def py2to3(cls):
        if hasattr(cls, '__unicode__'):
            cls.__str__ = lambda self: self.__unicode__()
        if hasattr(cls, '__nonzero__'):
            cls.__bool__ = lambda self: self.__nonzero__()
        return cls

3. 使用

@py2to3
class ConnectionCache(object):
  xxx