不能直接通过`locals（）在python中设置局部变量`

Question

我会保持这个简短。为什么会出现以下行为？你知道吗

>>> globals()['x'] = 5
>>> x
5
>>> def f():
...    locals()['y'] = 7
...    y
...
>>> f()
Traceback (most recent call last):
  File "<pyshell#32>", line 1, in <module>
    f()
  File "<pyshell#31>", line 3, in f
    y
NameError: name 'y' is not defined

下面是一个可以使用的示例：

import opcode
def foo():
    locals().update(opcode.opmap)
    #do stuff

Answer 1

The documentation for locals() includes：

Note: The contents of this dictionary should not be modified; changes may not affect the values of local and free variables used by the interpreter.