python logger中的序言和结尾 [英] Prologue and epilogue in python logger

问题描述

我希望创建一个记录器类，在第一次记录时.getLogger()将编写一个序言，并且一旦该过程结束记录器并编写一个结语

我的代码:

logger = logging.getLogger('name')
logger.info('HI')

预期输出:

2014-09-29 10:50:40,187 - INFO - ** My prologue **
2014-09-29 10:50:40,187 - INFO - HI
2014-09-29 10:50:40,187 - INFO - ** My epilogue **

解决方案

如前所述，我先前回答中的epiLoggers不是单子"，必须在将要使用它们的模块之间传递.

解决此问题的选项包括

• 将logger.Logger子类化(如果实际上可行，我还没有研究过)，
• 实施一种机制来创建和存储和检索EpiLogLogger，例如logger.getLogger(过于夸张的想法)
• 创建一个可在多个模块中使用的类似Singleton的epiLogger.

此解决方案适用于后者.

import logging

class epiLogger():
    _initialised = {}
    _finalised = {}

    def __init__(self, name):
        self.logger = logging.getLogger(name)
        self.name = name
        if not epiLogger._initialised.get(name):
            self.logger.addHandler(logging.StreamHandler())
            self.logger.setLevel(logging.INFO)
            self.logger.info('** My Prologue **')
            epiLogger._initialised[self.name] = True

    def info(self, the_info):
        self.logger.info(the_info)

    def __del__(self):
        if not self.__class__._finalised.get(self.name):
            self.logger.info('** My Epilogue **')
            self.__class__._finalised[self.name] = True

a = epiLogger("foo")

a.info("foo!")
a.info("bar!")
a.info("party!")

我知道这是一件好事，但请在此处阅读:

或者当然调查子类的logger.Logger :)

I wish to create a logger class that upon the first logging.getLogger() will write a prologue and once the process ends the logger with write an epilogue

my code:

logger = logging.getLogger('name')
logger.info('HI')

The expected output:

2014-09-29 10:50:40,187 - INFO - ** My prologue **
2014-09-29 10:50:40,187 - INFO - HI
2014-09-29 10:50:40,187 - INFO - ** My epilogue **

解决方案

As observed, the epiLoggers in my previous answers are not "singletons", and have to be passed around between modules that are going to use them.

Options for getting around this include

• subclassing logger.Logger (if that is in fact possible, which I have not investigated),
• implementing a mechanism to create and store and retrive epiLoggers like logger.getLogger (ridiculously overblown idea)
• creating a singleton-like epiLogger that can be used in multiple modules.

This solution does the latter.

import logging

class epiLogger():
    _initialised = {}
    _finalised = {}

    def __init__(self, name):
        self.logger = logging.getLogger(name)
        self.name = name
        if not epiLogger._initialised.get(name):
            self.logger.addHandler(logging.StreamHandler())
            self.logger.setLevel(logging.INFO)
            self.logger.info('** My Prologue **')
            epiLogger._initialised[self.name] = True

    def info(self, the_info):
        self.logger.info(the_info)

    def __del__(self):
        if not self.__class__._finalised.get(self.name):
            self.logger.info('** My Epilogue **')
            self.__class__._finalised[self.name] = True

a = epiLogger("foo")

a.info("foo!")
a.info("bar!")
a.info("party!")

I know that this feels like a good thing to do, but read here: http://jalf.dk/blog/2010/03/singletons-solving-problems-you-didnt-know-you-never-had-since-1995/. I would seriously ask yourself "actually, might it be best in the long run to pass each epiLogger around to where it belongs?"

Or of course investigate subclassing logger.Logger :)

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