Change logging "print" function to "tqdm.write" so logging doesn't interfere with progress bars

Question

I have a simple question: How do I change the built-in Python logger's print function to tqdm.write such that logging messages do not interfere with tqdm's progress bars? Thanks!

Answer 1

You need a custom logging handler:

import logging
import tqdm

class TqdmLoggingHandler(logging.Handler):
    def __init__(self, level=logging.NOTSET):
        super().__init__(level)

    def emit(self, record):
        try:
            msg = self.format(record)
            tqdm.tqdm.write(msg)
            self.flush()
        except (KeyboardInterrupt, SystemExit):
            raise
        except:
            self.handleError(record)  

and then add this to the logging chain:

import time

log = logging.getLogger(__name__)
log.setLevel(logging.INFO)
log.addHandler(TqdmLoggingHandler())
for i in tqdm.tqdm(range(100)):
    if i == 50:
        log.info("Half-way there!")
    time.sleep(0.1)

Edit: Fixed a bug in the call to super TqdmLoggingHandler's init method, that was pointed out by diligent reader @BlaineRogers in the comments. (If anyone wants to read further about this murky area of Python, I recommend https://fuhm.net/super-harmful/)