How to check if there is a missing argument

Question

I wrote this code:

def suma(num1,num2):

    if(isinstance(num1,int)) or (isinstance(num2,int)) :
       if num1<0 or num2<0:
            print("iavo")
       elif num1!=int(num1)or num2!=int(num2):
            print("iao")
       else:
            suma_a = num1+num2
            return suma_a
    else:
        print("ia")

I need to check whether there is a num1 or num2. If there is none, the program should print that there is a missing argument.

Answer 1

If you do not assign default values and a user did not supply two args you would get a TypeError: suma() missing 1 required positional argument before you got into the function at all:

def suma(num1=None,num2=None):
     # make sure user has entered two args and both are numbers
    if num1 is None or num2 is None:
        return "You Must choose two numbers"
    # rest of code

Answer 2

That function will throw an error if you don't send both numbers. There is no way to leave out an argument in your function.

If you did i.e. something like:

def summ(a, b=None):
    return a+b

then you could leave out b, however this will throw an unsupported operand error again because you can't add a number and None.

You can check if you have all numbers present if you're calling that function in the scope of some other function, or in a class, you can wrap it in a try except block and try to handle the error like shown in the dumbest example possible:

try: 
    summ(1)
except: 
    print("Missing arguments, you can't add numbers and None in Python!"\
          " Please send b.")