kargs and args behaving strange

Question

I was just testing a piece of code with kwargs and args. But why args is picking up all the passed parameters in the following code ?

def myfunc(color='red',*args,**kwargs):
    print (args)
    print (color) 
    print (kwargs)
names=["Ramesh","Krishna"]
ages={'Ramesh_age':20,'Krishna_age':10,'Kanchi_age':5}

myfunc('blue',names,ages)

Result:

(['Ramesh', 'Krishna'], {'Krishna_age': 10, 'Ramesh_age': 20, 'Kanchi_age': 5})
blue
{}

why it all including ages has been assigned to ages and kwargs is empty ?

`myfunc('blue',*names, **ages)` – Mr_U4913 Oct 11 '19 at 18:52 — Mr_U4913, Oct 11 '19 at 18:52
Because you only passed positional args – jonrsharpe Oct 11 '19 at 18:53 — jonrsharpe, Oct 11 '19 at 18:53

score 2 · Answer 1 · answered Oct 11 '19 at 18:56

2

You need to use *names to unwrap names and **ages to unwrap ages.

Like this myfunc('blue', *names, **ages)

answered Oct 11 '19 at 18:56

Jones Romão

21
3

score 2 · Answer 2 · answered Oct 11 '19 at 18:59

To be precise, kwargs is not picking up any values because kwargs looks for key - value pairs.

The way you passed your arguements, there is no key value pairs. You passed along

ages={'Ramesh_age':20,'Krishna_age':10,'Kanchi_age':5}

as a whole object, instead of destructuring the object and passing it as individual key value pairs.

As others have pointed out, the correct way is to destructure the object as seperate key value pairs as:

**ages

codrelphi · Answer 3 · 2019-10-11T19:10:06.983

args looks for any values and kwargs looks for any key-value pairs. When you call your function, you have to specify * before args and ** before kwargs. It is the way Python works.

Here's your code:

def myfunc(color='red',*args,**kwargs):
    print (args)
    print (color) 
    print (kwargs)

names=["Ramesh","Krishna"]
ages={'Ramesh_age':20,'Krishna_age':10,'Kanchi_age':5}

# to call the function
myfunc('blue', *names, **ages)

Here's the results:

('Ramesh', 'Krishna')
blue
{'Ramesh_age': 20, 'Krishna_age': 10, 'Kanchi_age': 5}

Explanations can be found here and here

kargs and args behaving strange

3 Answers3