Argument parser for verbosity, where more `-v` is to be used to increase the logging level

verbosity-argument-parser.py

# Copyright (c) 2018 Genome Research Limited
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import logging
from typing import Dict

VERBOSE_PARAMETER_KEY = "short_parameter"
DEFAULT_LOG_VERBOSITY_KEY = "default_verbosity"

verbosity_parser_configuration = {
    VERBOSE_PARAMETER_KEY: "v",
    DEFAULT_LOG_VERBOSITY_KEY: logging.ERROR
}


def get_verbosity(parsed_arguments: Dict) -> int:
    """
    Gets the verbosity level from parsed arguments.
    
    Assumes parameter is being parsed similarly to:
    ```
    parser.add_argument(f"-{verbosity_parser_configuration[VERBOSE_PARAMETER_KEY]}", action="count", default=0,
                        help="increase the level of log verbosity (add multiple increase further)")
    ```

    Parsed arguments can be gathered into an appropriate dict as show below:
    ```
    assert type(argument_parser) is ArgumentParser
    parsed_arguments = {x.replace("_", "-"): y for x, y in vars(argument_parser.parse_args(arguments)).items()}
    ```
    :param parsed_arguments: parsed arguments in dictionary form
    :return: the verbosity level implied
    :raises ValueError: if the logging level is too high
    """
    verbosity_parameter = verbosity_parser_configuration[VERBOSE_PARAMETER_KEY]
    verbosity = verbosity_parser_configuration[DEFAULT_LOG_VERBOSITY_KEY] - (
            int(parsed_arguments.get(verbosity_parameter)) * 10)
    if verbosity < 10:
        raise ValueError("Cannot provide any further logging - reduce log verbosity")
    assert verbosity <= logging.CRITICAL
    return verbosity