Python，日志：如何使用字典配置自定义处理程序？

Question

这段内容是关于Python 3.2中的日志模块（在GNU/Linux x86_64系统上）的：有没有办法用字典配置来设置一个自定义的处理器？

这是我尝试的代码：

import logging
import logging.config

class CustomHandler(logging.StreamHandler):
    pass

logconfig = {
    'version': 1,
    'handlers': {
        'console': {
            'class': 'CustomHandler',
        }
    },
    'loggers': {
        'custom': {
            'handlers': ['console'],
        }
    }
}
logging.config.dictConfig(logconfig)
logger = logging.getLogger('custom')
logger.error('Error message')

当然，这段代码是无法运行的。输出结果是：

Traceback (most recent call last):
  File "/usr/lib/python3.2/logging/config.py", line 390, in resolve
    found = self.importer(used)
ImportError: No module named CustomHandler

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/usr/lib/python3.2/logging/config.py", line 569, in configure
    handler = self.configure_handler(handlers[name])
  File "/usr/lib/python3.2/logging/config.py", line 698, in configure_handler
    klass = self.resolve(config.pop('class'))
  File "/usr/lib/python3.2/logging/config.py", line 403, in resolve
    raise v
  File "/usr/lib/python3.2/logging/config.py", line 390, in resolve
    found = self.importer(used)
ValueError: Cannot resolve 'CustomHandler': No module named CustomHandler

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "./prova.py", line 91, in <module>
    logging.config.dictConfig(logconfig)
  File "/usr/lib/python3.2/logging/config.py", line 777, in dictConfig
    dictConfigClass(config).configure()
  File "/usr/lib/python3.2/logging/config.py", line 574, in configure
    '%r: %s' % (name, e))
ValueError: Unable to configure handler 'console': Cannot resolve 'CustomHandler': No module named CustomHandler

在源代码中有一个我完全不理解的importer方法……你有什么想法吗？

谢谢！

Answer 1

你需要告诉程序在哪里可以找到 CustomHandler 这个类。这个字符串应该包含它所在的模块（可能还有包名）。如果你直接运行这个脚本，可以用 __main__.CustomHandler。如果不是，就用 your_module.CustomHandler，其中 your_module 需要替换成包含这个类的模块的名字。