import logging
class ProgressConsoleHandler(logging.StreamHandler):
"""
A handler class which allows the cursor to stay on
one line for selected messages
"""
on_same_line = False
def emit(self, record):
try:
msg = self.format(record)
stream = self.stream
same_line = hasattr(record, 'same_line')
if self.on_same_line and not same_line:
stream.write(self.terminator)
stream.write(msg)
if same_line:
stream.write('... ')
self.on_same_line = True
else:
stream.write(self.terminator)
self.on_same_line = False
self.flush()
except (KeyboardInterrupt, SystemExit):
raise
except:
self.handleError(record)
if __name__ == '__main__':
import time
progress = ProgressConsoleHandler()
console = logging.StreamHandler()
logger = logging.getLogger('test')
logger.setLevel(logging.DEBUG)
logger.addHandler(progress)
logger.info('test1')
for i in range(3):
logger.info('remaining %d seconds', i, extra={'same_line':True})
time.sleep(1)
logger.info('test2')
Notice that only one handler is being registered, and the extra
keyword argument to let the handler know it should stay on one line. There is more logic in the emit()
method to handle changes between messages that should stay on one line and messages that need to have their own line.