[Tutor] logging to cmd.exe

[Albert-Jan Roskam]

Hi,


With Python 3.5 under Windows I am using the logging module to log messages to stdout (and to a file), but this occasionally causes logging errors because some characters cannot be represented in the codepage used by cmd.exe (cp850, aka OEM codepage, I think). What is the best way to prevent this from happening? The program runs fine, but the error is distracting. I know I can use s.encode(sys.stdout.encoding, 'replace') and log that, but this is ugly and tedious to do when there are many log messages. I also don't understand why %r (instead of %s) still causes an error. I thought that the character representation uses only ascii characters?!


import logging
import sys

assert sys.version_info.major > 2
logging.basicConfig(filename="d:/log.txt", level=logging.DEBUG,format='%(asctime)s %(message)s')
handler = logging.StreamHandler(stream=sys.stdout)
logger = logging.getLogger(__name__)
logger.addHandler(handler)

s = '\u20ac'
logger.info("euro sign: %r", s)



--- Logging error ---
Traceback (most recent call last):
  File "c:\python3.5\lib\logging\__init__.py", line 982, in emit
    stream.write(msg)
  File "c:\python3.5\lib\encodings\cp850.py", line 19, in encode
    return codecs.charmap_encode(input,self.errors,encoding_map)[0]
UnicodeEncodeError: 'charmap' codec can't encode character '\u20ac' in position 12: character maps to <undefined>
Call stack:
  File "q:\temp\logcheck.py", line 10, in <module>
    logger.info("euro sign: %r", s)
Message: 'euro sign: %r'
Arguments: ('\u20ac',)


Thanks in advance for your replies!


Albert-Jan