Decorator to print function call details - parameters names and effective values

Question

I want to make a function that being a decorator to another function will print that function call details - parameters names and effective values. My current implementation

Answer 1

Here's how I solved it in Python 3, based on aliteralmind's answer, put more cleanly (PEP8) if I may say so. Majority of the inspiration for the cleanup came from the (currently) accepted answer by Robert King.

Code (test.py):

#!/usr/bin/env python3

import functools
import inspect
import logging
import time


class CustomFormatter(logging.Formatter):
    """
    Custom formatter, overrides funcName with value of name_override if it exists

    Inspired by; https://stackoverflow.com/a/7004565/1503549
    """
    def format(self, record):
        if hasattr(record, 'func_name'):
            record.funcName = record.func_name
        return super(CustomFormatter, self).format(record)


def log_function_entry_and_exit(decorated_function):
    """
    Function decorator logging entry + exit and parameters of functions.

    Entry and exit as logging.info, parameters as logging.DEBUG.
    """

    @functools.wraps(decorated_function)
    def wrapper(*dec_fn_args, **dec_fn_kwargs):
        # Log function entry
        func_name = decorated_function.__name__
        name_dict = dict(func_name=func_name)
        logging.info(f"Entering {func_name}()...", extra=name_dict)

        # Log function params (args and kwargs)
        func_args = inspect.signature(decorated_function).bind(*dec_fn_args, **dec_fn_kwargs).arguments
        func_args_str = ', '.join(
            f"{var_name} = {var_value}"
            for var_name, var_value
            in func_args.items()
        )
        logging.debug(f"\t{func_args_str}", extra=name_dict)

        # Execute wrapped (decorated) function:
        out = decorated_function(*dec_fn_args, **dec_fn_kwargs)

        time.sleep(1)   # Test to ensure timestamp is real
        logging.info(f"Done running {func_name}()!", extra=name_dict)

        return out
    return wrapper


@log_function_entry_and_exit
def func2(*args, **kwargs):
    print('\t\thello')


@log_function_entry_and_exit
def func1(a, b, c):
    func2(1, 2, 3, 4, b=5)
    print('Hello2!')


if __name__ == '__main__':
    log = logging.getLogger()

    # Must get handler to set format
    handler = logging.StreamHandler()   # Get default root logger
    handler.setFormatter(
        CustomFormatter(
            (
                '[%(asctime)s]'
                ' %(levelname)s:%(funcName)s():%(lineno)s>'
                ' %(message)s'
            ),
            datefmt='%Y-%m-%dT%H:%M:%S',
        )
    )

    # Set logLevel
    log.setLevel(logging.DEBUG)
    handler.setLevel(logging.DEBUG)

    # Combine the two again
    log.addHandler(handler)

    log.info('yolo!', extra=dict(func_name='__main__'))

    func1(2, b="y", c={'z': 4})

Output:

[2020-06-11 22:22:15] 0 x10an14@x10-desktop:~/Desktop/testy
-> $ python3 test.py 
[2020-06-11T22:22:53] INFO:__main__():88> yolo!
[2020-06-11T22:22:53] INFO:func1():33> Entering func1()...
[2020-06-11T22:22:53] DEBUG:func1():42>     a = 2, b = y, c = {'z': 4}
[2020-06-11T22:22:53] INFO:func2():33> Entering func2()...
[2020-06-11T22:22:53] DEBUG:func2():42>     args = (1, 2, 3, 4), kwargs = {'b': 5}
        hello
[2020-06-11T22:22:54] INFO:func2():48> Done running func2()!
Hello2!
[2020-06-11T22:22:55] INFO:func1():48> Done running func1()!
[2020-06-11 22:22:55] 0 x10an14@x10-desktop:~/Desktop/testy
-> $ 

When I get the magical resources known as "time and energy", I'm interested in playing around with LOG_FORMAT, and figure out how I can replace the wrapper substring with say filename and line number of function invocation =)

EDIT(2020-06-11): Fixed wrapper issue after prompt from @Gahan's comment (dated 2020-06-10).

It seems to be impossible (ref. https://stackoverflow.com/a/8339710/1503549) to have a wrapper report (via the logging module) the line-number of the wrapped / decorated function. Maybe wrapt could be leveraged for this purpose?