Python sys._getframe

Question

/mypath/test.py

import sys

def test():
    frame = sys._getframe(0)
    f = frame.f_code.co_filename
    print('f:', f)
    print('co_filename1:', frame.f_code.co_filename)
    while frame.f_code.co_filename == f:
        frame = frame.f_back
    print('co_filename2:', frame.f_code.co_filename)

test()

运行它并得到:

f: /mypath/test.py
co_filename1: /mypath/test.py
Traceback (most recent call last):
  File "/mypath/test.py", line 13, in <module>
    test()
  File "/mypath/test.py", line 9, in test
    while frame.f_code.co_filename == f:
AttributeError: 'NoneType' object has no attribute 'f_code'

为什么frame.f_code在while循环中出现NoneType Error，但可以照常打印？谢谢~

Answer 1

每当您运行frame = frame.f_back时，您都会返回到上一个代码帧。然而，当您位于最顶层的帧时，f_back 属性包含 None (如“没有前一帧”) - 因此您应该在该点中断 while 循环。只需添加一个额外的条件即可，例如:

while frame and frame.f_code.co_filename == f:
        frame = frame.f_back