Python使用常见的记录器类mixin和类继承进行日志记录

Question

我想创建一个Python日志记录类,它可以作为记录配置的常用方法继承,但是从父级单独控制基类的日志记录级别.这类似于如何在多个模块中使用python日志记录.Vinay Sajip使用LogMixin 的答案非常接近.以下是我稍加修改的版本.

我的大多数类都继承了较小的类.例如:

filename:LogMixin.py

import logging, logging.config
import yaml
class LogMixin(object):
    __loggerConfigured = False
    @property
    def logger(self):
        if not self.__loggerConfigured:
            with open('log_config.yaml', 'rt') as f:
                config = yaml.load(f.read())
                logging.config.dictConfig(config)
            self.__loggerConfigured = True
        name = '.'.join([self.__class__.__name__])
        return logging.getLogger(name)

文件名:Base.py

from LogMixin import LogMixin
class Base(LogMixin):
    def __init__(self):
        self.logger.debug("Debug Base")
    def run_base(self):
        self.logger.debug("Debug Running Base")
        self.logger.info("Info Running Base")
if __name__ == '__main__':
    my_base = Base()
    my_base.run_base()         

filename:Parent.py

from Base import Base
class Parent(Base):
    def __init__(self):
        self.logger.debug("Debug Parent")
    def run_parent(self):
        self.logger.debug("Debug Running Parent")
        self.logger.info("Info Running Parent")

if __name__ == '__main__':
    my_parent = Parent()
    my_parent.run_base()
    my_parent.run_parent()

filename:log_config.yaml

---
version: 1
disable_existing_loggers: False

# Configuring the default (root) logger is highly recommended
root:
    level: WARNING
    handlers: [console]

# Configuration for logger set with logging.getLogger(NAME)
loggers:
    Base:
        level: INFO
        handlers: [console]
        propagate: no
    Parent:
        level: DEBUG
        handlers: [console]
        propagate: no

formatters:
    simple:
        format: "%(asctime)s - %(name)s - %(levelname)s - %(message)s"

handlers:
    console:
        class: logging.StreamHandler
        formatter: simple
        stream: ext://sys.stdout
...

我得到了常见日志记录配置的好处.但是,我希望独立控制Base和Parent的日志级别.使用上面的配置文件,我得到:

$ python Base.py                 
2015-03-16 00:06:23,716 - Base - INFO - Info Running Base
$ python Parent.py                
2015-03-16 00:06:19,682 - Parent - DEBUG - Debug Parent
2015-03-16 00:06:19,682 - Parent - DEBUG - Debug Running Base
2015-03-16 00:06:19,682 - Parent - INFO - Info Running Base
2015-03-16 00:06:19,682 - Parent - DEBUG - Debug Running Parent
2015-03-16 00:06:19,682 - Parent - INFO - Info Running Parent

我理解为什么我得到这个,我只有一个记录器"父".但是,一般来说,我宁愿得到以下内容:

$ python Base.py                 
2015-03-16 00:06:23,716 - Base - INFO - Info Running Base
$ python Parent.py                
2015-03-16 00:06:19,682 - Parent - DEBUG - Debug Parent
2015-03-16 00:06:19,682 - Base - INFO - Info Running Base
2015-03-16 00:06:19,682 - Parent - DEBUG - Debug Running Parent
2015-03-16 00:06:19,682 - Parent - INFO - Info Running Parent

(注意没有与Base.py相关的DEBUG).
甚至更好:

$ python Base.py                 
2015-03-16 00:06:23,716 - Base - INFO - Info Running Base
$ python Parent.py                
2015-03-16 00:06:19,682 - Parent - DEBUG - Debug Parent
2015-03-16 00:06:19,682 - Parent.Base - INFO - Info Running Base
2015-03-16 00:06:19,682 - Parent - DEBUG - Debug Running Parent
2015-03-16 00:06:19,682 - Parent - INFO - Info Running Parent

(注意名称是Parent.Base,所以我可以看到继承.)这可以通过一个简单的LogMixin类实现吗？

Answer 1

在您的示例中，当self.logger调用 时，它会调用self.__class__.__name__. 这始终是 mro 中的第一个类，即被调用来创建实例的类。

解决这个问题的方法是名称修改，它确保类方法使用相同的类属性。

import logging

class Base:
    __logger = logging.getLogger('Base')

    def __init__(self):
        self.__logger.error('init base')

    def func_base(self):
        self.__logger.error('func base')

class Parent(Base):
    __logger = logging.getLogger('Base.Parent')

    def func_parent(self):
        self.__logger.error('func parent')

元类可用于确保记录器在定义时一次创建并归属于该类。

import logging
import sys

logging.basicConfig(stream=sys.stdout)

class MetaBase(type):
    def __init__(cls, *args):
        super().__init__(*args)

        # Explicit name mangling
        logger_attribute_name = '_' + cls.__name__ + '__logger'

        # Logger name derived accounting for inheritance for the bonus marks
        logger_name = '.'.join([c.__name__ for c in cls.mro()[-2::-1]])

        setattr(cls, logger_attribute_name, logging.getLogger(logger_name))

class Base(metaclass=MetaBase):
    def __init__(self):
        self.__logger.error('init base')

    def func_base(self):
        self.__logger.error('func base')

class Parent(Base):
    def func_parent(self):
        self.__logger.error('func parent')

p = Parent()
p.func_base()
p.func_parent()

结果是：

ERROR:Base:init base
ERROR:Base:func base
ERROR:Base.Parent:func parent

我简化了示例来演示关键概念。应该跨文件和配置文件工作。