Why args type is always tuple, when passed it as argument to the function.

[praveena]

I am passing list argument to the function. But type of args is always tuple.
I would like to know the specific reason for this behavior?

>>> def fun(*args):
...     print "type of args :", type(args)
... 
>>> l=[1,2,3,4]
>>> fun(l)
type of args : <type 'tuple'>

[Gribouillis]

It is because of the * that you wrote in fun(*args). This * is used when one writes a variadic function that takes a variable number of arguments. If you want to pass a single list argument, use def fun(args).

[praveena]

Hi Gribouillis,
Thanks for the replay.
Still my doubt is not cleared. why only tuple is created because of * in fun(*args), why can't list?

Regards,
Praveen.

[Gribouillis]

It is the way variadic functions work in python. If you define fun(*args), then you can call
fun(7,8,9) and you have args = (7, 8, 9), a tuple with 3 items. If you call
fun(7), you have args = (7,) a tuple with a single item. Finally, if you call fun([ 3, 4, 5]), then args = ([3, 4, 5],), a tuple which single item is a list.

[wavic]

https://docs.python.org/3.6/tutorial/con...ment-lists

[praveena]

Hi Gribouillis and Wavic,

Thanks for the reply and got clarified.

Regards,
Praveen