Receiving Arguments via Pointers in Python

Question

I have a class whose function defined like this. My intention is to send multiple arguments to it .

For testing, I called it as :class_name("argument1","argument2"), and it says: __init__accepts atmost 1 arguments , 3 given

def __init__(self, **options):
    for name in options:
        self.__dict__[name] = options[name]

What is the proper way to handle this ?

Any suggestions welcome......

That is [a good question](http://stackoverflow.com/questions/6656178/how-do-you-articulate-the-and-specifiers-when-reading-python-aloud)! — johnsyweb, Jul 11 '11 at 20:33

GWW · Accepted Answer · 2011-07-11T02:57:15.200

You want to use one asterisk instead of two. Double asterisks are for named arguments. There is a nice explanation in the python documentation if you are interested in reading further.

def __init__(self, *options):
    for name in options:
        self.__dict__[name] = name

However, from your code I think the real issue is that you are calling your function incorrectly.

You would want to call it like:

class_name(argument1="some value")

def __init__(self, **options):
    for name,val in options.iteritems():
        self.__dict__[name] = val

score 4 · Answer 2 · answered Jul 11 '11 at 03:16

4

Here is a simpler way to write it

def __init__(self, **options):
    vars(self).update(options)

answered Jul 11 '11 at 03:16

John La Rooy

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@gnibbler - the Python docs warn against modifying the dict returned by `vars` - see http://docs.python.org/library/functions.html#vars – A Lee Jul 11 '11 at 21:23
@A Lee, when `vars` is called without an argument is is equivalent to `locals()`, and this result should not be modified. In the case of an instance, it simply returns the `__dict__` which is of course ok to modify. – John La Rooy Jul 12 '11 at 00:27

score 3 · Answer 3 · answered Jul 11 '11 at 02:57

The * form collects positional arguments:

def __init__(self, *options):

and the ** form collects keyword arguments:

def __init__(self, **options):

You're providing 2 positional arguments plus the instance as self, but it's defined to expect only 1 positional argument self.

Receiving Arguments via Pointers in Python

3 Answers3

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