Question

我想将某些任意代码的print()语句重定向到正确的日志记录功能。

不幸的是，以下代码仅在print()获得单个参数时起作用。

import logging

logging.basicConfig(filename="logname",
                    filemode='a',
                    format='%(asctime)s,%(msecs)03d %(name)s %(levelname)s %(message)s',
                    datefmt='%D %H:%M:%S',
                    level=logging.DEBUG)

print = logging.debug
print("hallo")
print("makes", "error")

这会产生以下日志文件：

03/30/18 14:06:11,881 root DEBUG hallo

控制台中出现以下错误：

Connected to pydev debugger (build 173.4674.37)
--- Logging error ---
Traceback (most recent call last):
  File "/home/user/anaconda3/lib/python3.6/logging/__init__.py", line 992, in emit
    msg = self.format(record)
  File "/home/user/anaconda3/lib/python3.6/logging/__init__.py", line 838, in format
    return fmt.format(record)
  File "/home/user/anaconda3/lib/python3.6/logging/__init__.py", line 575, in format
    record.message = record.getMessage()
  File "/home/user/anaconda3/lib/python3.6/logging/__init__.py", line 338, in getMessage
    msg = msg % self.args
TypeError: not all arguments converted during string formatting
Call stack:
  File "/home/user/install_dir/pycharm/2017-12-12-ultimate-edition/pycharm-2017.3/helpers/pydev/pydevd.py", line 1668, in <module>
    main()
  File "/home/user/install_dir/pycharm/2017-12-12-ultimate-edition/pycharm-2017.3/helpers/pydev/pydevd.py", line 1662, in main
    globals = debugger.run(setup['file'], None, None, is_module)
  File "/home/user/install_dir/pycharm/2017-12-12-ultimate-edition/pycharm-2017.3/helpers/pydev/pydevd.py", line 1072, in run
    pydev_imports.execfile(file, globals, locals)  # execute the script
  File "/home/user/install_dir/pycharm/2017-12-12-ultimate-edition/pycharm-2017.3/helpers/pydev/_pydev_imps/_pydev_execfile.py", line 18, in execfile
    exec(compile(contents+"\n", file, 'exec'), glob, loc)
  File "/home/user/PycharmProjects/my_project/attic.py", line 12, in <module>
    print("makes", "error")
Message: 'makes'
Arguments: ('error',)

Process finished with exit code 0

如何更改代码以使其适用于print()的任意数量的参数？

Answer 1

print不再是自己了，因为您将print重新定义为logging.debug，debug仅将第一个参数作为消息。但是，您可以采用不同的方式定义print，如下所示：

def print(*args, sep=" ", **kwargs):
    return logging.debug(sep.join(map(lambda x: str(x), args)), **kwargs)

这会失去使用debug *args格式化字符串的功能。

args 是使用字符串合并到msg的参数格式化运算符（请注意，这意味着您可以使用关键字在格式字符串中，与单个字典参数一起使用。）

我建议您使用StreamHandler而不是重新定义print。

如何将打印重定向到具有多个打印参数的日志记录？

1 个答案: