[flask源码梳理]之四 源码栈的维持

flask源码对栈的维持

class LocalStack(object):
    def __init__(self):
        self._local = Local()

    def push(self,value):
        rv = getattr(self._local, 'stack', None) # self._local.stack =>local.getattr
        if rv is None:
            self._local.stack = rv = [] #  self._local.stack =>local.setattr
        rv.append(value) # self._local.stack.append(666)
        return rv


    def pop(self):
        """Removes the topmost item from the stack, will return the
        old value or `None` if the stack was already empty.
        """
        stack = getattr(self._local, 'stack', None)
        if stack is None:
            return None
        elif len(stack) == 1:
            return stack[-1]
        else:
            return stack.pop()

    def top(self):
        try:
            return self._local.stack[-1]
        except (AttributeError, IndexError):
            return None



class RequestContext(object):
    def __init__(self):
        self.request = "xx"
        self.session = 'oo'



_request_ctx_stack = LocalStack()

_request_ctx_stack.push(RequestContext())


def _lookup_req_object(arg):

    ctx = _request_ctx_stack.top()

    return getattr(ctx,arg) # ctx.request / ctx.session

request = functools.partial(_lookup_req_object,'request')
session = functools.partial(_lookup_req_object,'session')


print(request())
print(session())

 

 

 

 

更新中。。。