CODEWITHSUNDEEP
pythonctypesbuilt-in
duan xingzhe
duan xingzhe

Reputation: 1

I don't know why it is wrong when I import ctypes

I changed the definition of the builtin function len, then I tried to import the ctypes module.But I don't know why it occurs an error when I did that.Here is my code:

import builtins

def func(obj):
    print("Length: %d" % len(obj))
builtins.len = lambda obj: "Bad!!!"

import ctypes

Then here is the tracback of the error:

Traceback (most recent call last):


  File "<stdin>", line 1, in <module>
  File "<frozen importlib._bootstrap>", line 969, in _find_and_load
  File "<frozen importlib._bootstrap>", line 958, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 673, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 661, in exec_module
  File "<frozen importlib._bootstrap_external>", line 772, in get_code
  File "<frozen importlib._bootstrap_external>", line 491, in _code_to_bytecode
  File "<frozen importlib._bootstrap_external>", line 42, in _w_long
ValueError: invalid literal for int() with base 10: 'Bad!!!'
Error in sys.excepthook:
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/apport_python_hook.py", line 53, in apport_excepthook
    if not enabled():
  File "/usr/lib/python3/dist-packages/apport_python_hook.py", line 24, in enabled
    import re
  File "<frozen importlib._bootstrap>", line 969, in _find_and_load
  File "<frozen importlib._bootstrap>", line 958, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 673, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 661, in exec_module
  File "<frozen importlib._bootstrap_external>", line 772, in get_code
  File "<frozen importlib._bootstrap_external>", line 491, in _code_to_bytecode
  File "<frozen importlib._bootstrap_external>", line 42, in _w_long
ValueError: invalid literal for int() with base 10: 'Bad!!!'

Original exception was:
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<frozen importlib._bootstrap>", line 969, in _find_and_load
  File "<frozen importlib._bootstrap>", line 958, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 673, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 661, in exec_module
  File "<frozen importlib._bootstrap_external>", line 772, in get_code
  File "<frozen importlibbootstrap_external>", line 491, in _code_to_bytecode
  File "<frozen importlib._bootstrap_external>", line 42, in _w_long
ValueError: invalid literal for int() with base 10: 'Bad!!!'

This puzzles me a lot. Thanks very much if someone can help me!

Upvotes: 0

Views: 232

Answers (1)

Arount
Arount

Reputation: 10431

Because your len function returns non integer string.

You just ran in the exact same behavior you could have with:

>>> int("I should know playing with builtins is always a bad thing")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: invalid literal for int() with base 10: 'lol'

Try to update your code like:

builtins.len = lambda obj: "123"

To see it.

Upvotes: 2

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