basic general all-purpose python file template

basic.py

"""
{USAGE}
python thisfile.py param1
"""
import sys
import os
import pprint as pp
import argparse
import logging
import traceback
try:
    import tqdm
except:
    pass

#logging.basicConfig(level=logging.WARNING)
logger = logging.getLogger(__name__)

MB = 1024 * 1024

# create console handler and set level to debug
ch = logging.handlers.RotatingFileHandler('extractor.log', mode='a', maxBytes=50 * MB, backupCount=5, encoding='utf-8')
ch.setLevel(logging.INFO)

# create formatter
formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')

# add formatter to ch
ch.setFormatter(formatter)

# add ch to logger
app.logger.addHandler(ch)
app.logger.setLevel(logging.INFO)

logger.info('*** STARTING EXTRACTOR ***')
logger.debug('debug message')
logger.info('info message')
logger.warn('warn message')
logger.error('error message')
logger.critical('critical message')

def factorial(n):
    """Return the factorial of n, an exact integer >= 0.

    >>> [factorial(n) for n in range(6)]
    [1, 1, 2, 6, 24, 120]
    >>> factorial(30)
    265252859812191058636308480000000
    >>> factorial(-1)
    Traceback (most recent call last):
        ...
    ValueError: n must be >= 0

    Factorials of floats are OK, but the float must be an exact integer:
    >>> factorial(30.1)
    Traceback (most recent call last):
        ...
    ValueError: n must be exact integer
    >>> factorial(30.0)
    265252859812191058636308480000000

    It must also not be ridiculously large:
    >>> factorial(1e100)
    Traceback (most recent call last):
        ...
    OverflowError: n too large
    """

    import math
    if not n >= 0:
        raise ValueError("n must be >= 0")
    if math.floor(n) != n:
        raise ValueError("n must be exact integer")
    if n+1 == n:  # catch a value like 1e300
        raise OverflowError("n too large")
    result = 1
    factor = 2
    while factor <= n:
        result *= factor
        factor += 1
    return result


def main(args):
    try:
        pass
    except:
        traceback.print_exc(file=sys.stdout)
        # import ipdb; ipdb.set_trace() # debugging starts here


if __name__ == '__main__':
    # Parses the command line
    # https://docs.python.org/3/library/argparse.html
    parser = argparse.ArgumentParser(description='Basic command line Python script')
    # parser.add_argument('name', type=str, help='random param', default='', nargs='?', action='store')
    # parser.add_argument('values', type=, help='list of numbers', default='', nargs='*')
    parser.add_argument('--test', '-t', help='executes a internal self-test', action='store_true')
    parser.add_argument('--verbose', '-v', action='count')
    parser.add_argument('--version', action='version', version='%(prog)s 1.0')

    args = parser.parse_args()

    # configures the logger and verbosity level
    verbose_level = args.verbose
    if verbose_level == 1:
        logger.setLevel(logging.INFO)
    if verbose_level >= 2:
        logger.setLevel(logging.DEBUG)

    logger.info('*** Begin ***')


    if args.test:
        logger.info('*** Self Testing ***')
        import doctest
        doctest.testmod(verbose=True)
    else:
        main(args)

    logger.info('*** End ***')