调试

1 try:
2     raise Exception('This is the error message.')
3 except Exception as err:
4     print('An exception happened: ' + str(err))

out: An exception happened: This is the error message.

 1 import traceback
 2 try:
 3     raise Exception('This is the error message.')
 4 except:
 5     errorfile = open('errorInfo.txt', 'w')
 6     errorfile.write(traceback.format_exc())
 7     errorfile.close()
 8     print('The traceback info was written to errorInfo.txt.')
 9 
10 out: The traceback info was written to errorInfo.txt.
11 
12 errorInfo.txt:
13 
14 Traceback (most recent call last):
15   File "d:\Code\Python\test.py", line 3, in <module>
16     raise Exception('This is the error message.')
17 Exception: This is the error message.

 1 test = 'open'
 2 assert test == 'open', 'The test need to be "open"'  #条件为True, 语句正常执行
 3 test = 'close'
 4 assert test == 'open', 'The test need to be "open"'
 5 
 6 out:
 7 Traceback (most recent call last):
 8   File "d:\Code\Python\test.py", line 4, in <module>
 9     assert test == 'open', 'The test need to be "open"'
10 AssertionError: The test need to be "open"

 1 import logging
 2 
 3 logging.debug('debug message')
 4 logging.info('info message')
 5 logging.warn('warn message')
 6 logging.error('error message')
 7 logging.critical('critical message') 
 8 
 9 out:  WARNING:root:warn message
10       ERROR:root:error message
11       CRITICAL:root:critical message
12 
13 #默认情况下，logging模块将日志打印到屏幕上(stdout)
14 #日志级别为WARNING(即只有日志级别高于WARNING的日志信息才会输出)
15 #日志级别大小关系为：CRITICAL > ERROR > WARNING > INFO > DEBUG > NOTSET

 1 import logging
 2 logging.basicConfig: logging.basicConfig(level=logging.DEBUG,
 3                                          format='%(asctime)s %(filename)s[line:%(lineno)d]%(levelname)s %(message)s',
 4                                          datefmt='%a, %d %b %Y %H:%M:%S',
 5                                          filename='myapp.log',
 6                                          filemode='w')
 7 '''
 8 logging.basicConfig函数各参数:
 9 filename: 指定日志文件名
10 filemode: 和file函数意义相同，指定日志文件的打开模式，'w'或'a'
11 format: 指定输出的格式和内容，format可以输出很多有用信息，如上例所示:
12  　　%(levelno)s: 打印日志级别的数值
13  　　%(levelname)s: 打印日志级别名称
14  　　%(pathname)s: 打印当前执行程序的路径，其实就是sys.argv[0]
15  　　%(filename)s: 打印当前执行程序名
16  　　%(funcName)s: 打印日志的当前函数
17  　　%(lineno)d: 打印日志的当前行号
18  　　%(asctime)s: 打印日志的时间
19  　　%(thread)d: 打印线程ID
20  　　%(threadName)s: 打印线程名称
21  　　%(process)d: 打印进程ID
22  　　%(message)s: 打印日志信息
23 datefmt: 指定时间格式，同time.strftime()
24 level: 设置日志级别，默认为logging.WARNING
25 stream: 指定将日志的输出流，可以指定输出到sys.stderr,sys.stdout或者文件，默认输出到sys.stderr，当stream和filename同时指定时，stream被忽略
26 '''