def mutable_pair(x,y):
def get_item(index):
if index == 0:
return x
return y
def set_item(index , val):
nonlocal x,y
if index == 0:
x = val
else:
y = val
def make_dict():
contents = None
def make_rlist(first,rest):
return (first,rest)
def dispatch(message,key,value):
nonlocal contents
if message == 'push_first':
contents = make_rlist(mutable_pair(key, value), contents)
z = make_dict()
z('push_first')(2,4)
我有这个问题,当我试图运行此代码时,我得到下一个错误:
Traceback (most recent call last):
File "C:\Users\Michael\workspace\HomeWork1\src\tests.py", line 35, in <module>
z('push_first')(2,4)
TypeError: 'NoneType' object is not callable:
对错误之处的帮助会有所帮助
最佳答案
TypeError:“ NoneType”对象不可调用:make_dict
返回None
,因此z
是None
,z('push_first')
将不起作用。