What is Keyword arguments in python?

Question

I am writing a program that gets its parameters from a combination of config file (using configparser) and command line arguments (using argparse). Now I would also like the program to be able to _write_ a
configparser config file that contains only the parameters actually given on the commandline. Is there a simple way to determine which command line arguments were actually given on the commandline, i.e. does argparse.ArgumentParser() know which of its namespace members were actually hit during parse_args().

I have tried giving the arguments default values and then looking for those having a non-default value but this is really awkward, especially if it comes to non-string arguments. Also, parsing sys.argv looks clumsy because you have to keep track of short and long options with and without argument etc. i.e. all things that I got argparse for in the first place.

Answer 1

If you have some functions with many parameters and you want to specify only some of them, then you can give values for such parameters by naming them - this is called keyword arguments - we use the name (keyword) instead of the position (which we have been using all along) to specify the arguments to the function.

Example

def func(a, b=5, c=10):
    print 'a is', a, 'and b is', b, 'and c is', c

func(3, 7)
func(25, c=24)
func(c=50, a=100)

Output

a is 3 and b is 7 and c is 10
a is 25 and b is 5 and c is 24
a is 100 and b is 5 and c is 50