Flask上下文源码分析之threading.local拓展

try:
    from greenlet import getcurrent as get_ident  #获取协程id
except ImportError:
    try:
        from thread import get_ident  # 获取线程id
    except ImportError:
        from _thread import get_ident  # 获取线程id

class Local(object):
    def __init__(self):
        object.__setattr__(self, '__storage__', {})  # self.__storage__ = {}，类中有__setattr__方法，所以此处应该用这种方法来创建字段，否则会递归
        object.__setattr__(self, '__ident_func__', get_ident)  # self.__ident_func__ = get_ident，get_ident获取唯一id

    def __getattr__(self, name):
        try:
            return self.__storage__[self.__ident_func__()][name]  # 取值print(request.method)
        except KeyError:
            raise AttributeError(name)

    def __setattr__(self, name, value):  # request.method = "POST" 
        ident = self.__ident_func__()
        storage = self.__storage__
        try:
            storage[ident][name] = value   # 赋值到self.__storage__这个字典中，
        except KeyError:
            storage[ident] = {name: value}