python的_args和_kwargs参数

Question

#!/usr/bin/env python


class Countries(object):
        def __init__(self,*_args,**_kwargs):
                self.name = 'japan'
                self.continent = 'asia'
                self.capital = 'tokyo'
                print _args
                print _kwargs

        def display(self):
                print self.name, self.continent,self.capital




iraq = Countries('iraq','bagdad','asia')

iraq.display()

india = Countries('india','delhi','asia')

india.display()

I have written a self teaching example above.I know that irrespective of the parameters I am always assigning

'japan' , 'asia' , 'tokyo'

to the member variables of the class.I wrote the above in an attempt to understand

   *_args and **_kwargs

The output of the above program is as below

('iraq', 'bagdad', 'asia')
{}
japan asia tokyo
('india', 'delhi', 'asia')
{}
japan asia tokyo

where _args is ('iraq', 'bagdad', 'asia')

and __kwargs is {}

why is a null string being printed for _kwargs and all arguments printed as a list for _args

Answer 1

Because you aren't passing in any keyword arguments. If you did Countries('Iraq', capital='Bagdad') , then it would print something for kwargs.