Decorator to log all call parameters and return values for a function

log_calls.py

import sys


def log_calls(fh=sys.stderr):
    """Logs the function, args, kwargs and return value to a file handle
    """
    def decorator(func):
        def wrapper(*args, **kwargs):
            retval = func(*args, **kwargs)
            print(func, args, kwargs, retval, file=fh)
            return retval
        return wrapper
    return decorator


@log_calls()
def add(a, b=1):
    return a + b


print(add(2, b=3))

# Will print
# <function add at 0x103ea5950> (2,) {'b': 3} 5
# 5