源码

# -*- coding: utf-8 -*-
"""
flask._compat
~~~~~~~~~~~~~ Some py2/py3 compatibility support based on a stripped down
version of six so we don't have to depend on a specific version
of it. :copyright: © 2010 by the Pallets team.
:license: BSD, see LICENSE for more details.
""" import sys PY2 = sys.version_info[0] == 2
_identity = lambda x: x if not PY2:
text_type = str
string_types = (str,)
integer_types = (int,) iterkeys = lambda d: iter(d.keys())
itervalues = lambda d: iter(d.values())
iteritems = lambda d: iter(d.items()) from inspect import getfullargspec as getargspec
from io import StringIO def reraise(tp, value, tb=None):
if value.__traceback__ is not tb:
raise value.with_traceback(tb)
raise value implements_to_string = _identity else:
text_type = unicode
string_types = (str, unicode)
integer_types = (int, long) iterkeys = lambda d: d.iterkeys()
itervalues = lambda d: d.itervalues()
iteritems = lambda d: d.iteritems() from inspect import getargspec
from cStringIO import StringIO exec('def reraise(tp, value, tb=None):\n raise tp, value, tb') def implements_to_string(cls):
cls.__unicode__ = cls.__str__
cls.__str__ = lambda x: x.__unicode__().encode('utf-8')
return cls def with_metaclass(meta, *bases):
"""Create a base class with a metaclass."""
# This requires a bit of explanation: the basic idea is to make a
# dummy metaclass for one level of class instantiation that replaces
# itself with the actual metaclass.
class metaclass(type):
def __new__(cls, name, this_bases, d):
return meta(name, bases, d)
return type.__new__(metaclass, 'temporary_class', (), {}) # Certain versions of pypy have a bug where clearing the exception stack
# breaks the __exit__ function in a very peculiar way. The second level of
# exception blocks is necessary because pypy seems to forget to check if an
# exception happened until the next bytecode instruction?
#
# Relevant PyPy bugfix commit:
# https://bitbucket.org/pypy/pypy/commits/77ecf91c635a287e88e60d8ddb0f4e9df4003301
# According to ronan on #pypy IRC, it is released in PyPy2 2.3 and later
# versions.
#
# Ubuntu 14.04 has PyPy 2.2.1, which does exhibit this bug.
BROKEN_PYPY_CTXMGR_EXIT = False
if hasattr(sys, 'pypy_version_info'):
class _Mgr(object):
def __enter__(self):
return self
def __exit__(self, *args):
if hasattr(sys, 'exc_clear'):
# Python 3 (PyPy3) doesn't have exc_clear
sys.exc_clear()
try:
try:
with _Mgr():
raise AssertionError()
except:
raise
except TypeError:
BROKEN_PYPY_CTXMGR_EXIT = True
except AssertionError:
pass 解读 本模块主要是做了些兼容处理,主要从python2与其他版本进行比较。从这可以看出python2在编码等方面是有一定差异的,我们了解即可,以下一些关键语句就是对这种差异做兼容处理:
   text_type = unicode
string_types = (str, unicode)
   integer_types = (int, long)
   cls.__str__ = lambda x: x.__unicode__().encode('utf-8')
05-11 19:24