How to combine variable length arguments with keyword arguments in python?

Question

def addv(a,b,*args):
    sum = a + b
    for x in args:
        sum += x
    return sum

addv(b = 1,a = 2) # This is valid
addv(args = (1,2,3,4,5,6,7,8),b = 9, a = 10) #This is giving me unexpected keyword argument.

I learned that keyword arguments are essentially passed as tuples. So, in an attempt to combine both keyword and variable arguments, I did the above experiment.

Is there any way to do such a kind of thing or all variable arguments must be passed to the end while calling a function.

Your first example doesn't seem valid since the positional arguments follow keyword arguments. — G_M
– G_M, Commented Mar 3, 2018 at 6:31

Omar Einea · Accepted Answer · 2018-03-03 06:40:43Z

5

You should use the ** operator to catch key word arguments. like this:

def addv(*args, **kwargs):
    result = 0
    for x in args:
        result += x
    for x in kwargs.values():
        result += x
    return result

Or a shorter way (suggested by Delirious Lettuce):

def addv(*args, **kwargs):
    return sum(args) + sum(kwargs.values())

Now you can do this:

addv(b = 1, a = 2) # Outputs: 3
addv(1, 2, 3, 4, 5, 6, 7, 8, b = 9, a = 10) # Outputs: 55

edited Mar 3, 2018 at 6:40

answered Mar 3, 2018 at 6:32

Omar Einea

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4 Comments

G_M Over a year ago

sum as a variable name?

Omar Einea Over a year ago

@DeliriousLettuce oh, that's what you mean, I just copied the OP's code not noticing that xD

Olivier Melançon Over a year ago

Instead of saying "you are kidding", why not just say: "it's bad practice to overshadow built-in variable names"?

G_M Over a year ago

No problem! I just meant that you could simplify it like this if you use sum properly. return sum(args) + sum(kwargs.values())

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