我已经编写了一个Python包,它使用了日志记录
模块,并广泛使用了带有Python包装器的第三方C库。我能够将自己包中的消息打印到控制台,并将它们写入文件(每个处理程序具有不同的日志记录级别)。但是,我希望在日志文件中包含第三方库打印的消息,以便查看它们的发生顺序。这是我的MWE:
import logging
# Assume no direct access to this function. (e.g. c++ library)
def third_party_function():
print("Inside of 'third_party_function'.")
def my_helper():
logger.debug("Inside of 'my_helper', before third party call.")
third_party_function()
logger.warning("Finished with third party call.")
root_logger = logging.getLogger()
root_logger.setLevel(logging.NOTSET)
logger = logging.getLogger("mylogger")
stream_handler = logging.StreamHandler()
stream_handler.setLevel(logging.WARNING)
file_handler = logging.FileHandler(filename="progress.out")
file_handler.setLevel(logging.NOTSET)
logger.addHandler(stream_handler)
logger.addHandler(file_handler)
my_helper()
目前,屏幕的输出为:
Inside of 'third_party_function'.
Finished with third party call.
以及文件的进度。输出
包含
Inside of 'my_helper', before third party call.
Finished with third party call.
但是,所需的进度。out
文件已被删除
Inside of 'my_helper', before third party call.
Inside of 'third_party_function'.
Finished with third party call.
似乎没有一个记录器属于这个第三方库,因为它不是用Python编写的。
我希望避免设置sys。stdout
到一个文件(如此处所示),因为我希望保持一致,并始终使用日志记录
模块。同一个问题的另一个答案是定义了一个自定义类,但它似乎仍然无法捕获第三方消息。
您可以暂时将标准输出从第三方函数重定向到记录器。
使用您链接的答案中的StreamToLogger类:将Python“打印”输出重定向到记录器
def wrap_third_party_function():
stdout = sys.stdout # save for restoring afterwards
# redirect stdout to use a logger, with INFO level
sys.stdout = StreamToLogger(logging.getLogger("mylogger.thirdparty"), logging.INFO)
print("start third_party_function; stdout to log")
third_party_function()
sys.stdout = stdout # restore stdout
print("done third_party_function; stdout restored")
def my_helper():
logger.debug("Inside of 'my_helper', before third party call.")
wrap_third_party_function()
logger.warning("Finished with third party call.")
在控制台上,您将看到:
done third_party_function; stdout restored
Finished with third party call.
progress.out将有:
Inside of 'my_helper', before third party call.
start third_party_function; stdout to log
Inside of 'third_party_function'.
Finished with third party call.
添加格式化程序可以更容易地看到:
formatter = logging.Formatter("%(name)s %(levelname)-8s %(message)s")
stream_handler.setFormatter(formatter)
file_handler.setFormatter(formatter)
使用此配置,progress.out显示:
mylogger DEBUG Inside of 'my_helper', before third party call.
mylogger.thirdparty INFO start third_party_function; stdout to log
mylogger.thirdparty INFO Inside of 'third_party_function'.
mylogger WARNING Finished with third party call.