我在 python 代码中使用的第三方库(用 C 编写)发出警告。我希望能够使用
try
except
语法来正确处理这些警告。有办法做到这一点吗?
要将警告作为错误处理,只需使用以下命令:
import warnings
warnings.filterwarnings("error")
此后,您将能够捕获与错误相同的警告,例如这会起作用:
try:
some_heavy_calculations()
except RuntimeWarning:
breakpoint()
您还可以通过运行以下命令来重置警告行为:
warnings.resetwarnings()
附注添加此答案是因为评论中的最佳答案包含拼写错误:
filterwarnigns
而不是filterwarnings
。
引用Python手册(27.6.4.测试警告):
import warnings
def fxn():
warnings.warn("deprecated", DeprecationWarning)
with warnings.catch_warnings(record=True) as w:
# Cause all warnings to always be triggered.
warnings.simplefilter("always")
# Trigger a warning.
fxn()
# Verify some things
assert len(w) == 1
assert issubclass(w[-1].category, DeprecationWarning)
assert "deprecated" in str(w[-1].message)
这里有一个变体,可以让您更清楚地了解如何仅使用自定义警告。
import warnings
with warnings.catch_warnings(record=True) as w:
# Cause all warnings to always be triggered.
warnings.simplefilter("always")
# Call some code that triggers a custom warning.
functionThatRaisesWarning()
# ignore any non-custom warnings that may be in the list
w = filter(lambda i: issubclass(i.category, UserWarning), w)
if len(w):
# do something with the first warning
email_admins(w[0].message)
扩展 niekas 答案,但使用
catch_warnings
上下文管理器在上下文退出后将警告行为重置为默认值:
import warnings
with warnings.catch_warnings():
warnings.simplefilter("error")
# Code in this block will raise exception for a warning
# Code in this block will have default warning behaviour
捕获所有警告可能会出现问题。您可以捕获特定的警告。例如,我需要捕捉枕头警告:
import warnings
warnings.filterwarnings("error", category=Image.DecompressionBombWarning)
def process_images():
try:
some_process()
except Image.DecompressionBombWarning as e:
print(e)
在某些情况下,您需要使用ctypes将警告转化为错误。例如:
str(b'test') # no error
import warnings
warnings.simplefilter('error', BytesWarning)
str(b'test') # still no error
import ctypes
ctypes.c_int.in_dll(ctypes.pythonapi, 'Py_BytesWarningFlag').value = 2
str(b'test') # this raises an error
为了完整起见,您还可以导出环境变量:
PYTHONWARNINGS=error /usr/bin/run_my_python_utility