详解python Warning警告有哪些情况

DeprecationWarning  # 有关已弃用功能的警告的基类
PendingDeprecationWarning  # 有关不推荐使用功能的警告的基类
RuntimeWarning  # 有关可疑的运行时行为的警告的基类
SyntaxWarning  # 关于可疑语法警告的基类
UserWarning  # 用户代码生成警告的基类
FutureWarning  # 有关已弃用功能的警告的基类
ImportWarning  # 关于模块导入时可能出错的警告的基类
UnicodeWarning  # 与Unicode相关的警告的基类
BytesWarning  # 与bytes和bytearray相关的警告的基类
ResourceWarning  # 与资源使用相关的警告的基类。被默认警告过滤器忽略。

import warnings
warnings.simplefilter("always")
def fxn():
    warnings.warn("this is a warning", Warning)
with warnings.catch_warnings():
    warnings.simplefilter("ignore")
    fxn()
with warnings.catch_warnings(Warning):
    warnings.warn("this is a warning2", Warning)
warnings.warn("this is a warning3", Warning)
def fxn2():
    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.
    fxn2()
    # Verify some things
    assert len(w) == 1
    assert issubclass(w[-1].category, DeprecationWarning)
    assert "deprecated" in str(w[-1].message)