Optionally passing an extra dictionary to a method / function

Question

I am coding a function as follows:

def create_objection(name, position, **kwargs):
    dicct = {'name':name,
             'position':position}
    print(len(kwargs))
    dicct.update({'extra_info': kwargs})
    return dicct

This function is supposed to get ALWAYS name and position, and eventually a collection of key/value pairs in for or dictionaries. what I want is the following way of working:

create_objection('c1',{'t':1})

Output:

 0
 {'name': 'c1', 'position': {'t': 1}, 'extra_info': {}}

When I try this, then I get an error:

create_objection('c1',{'t':1},{'whatever':[3453,3453]},{'whatever2':[34,34]})

The error:

TypeError                                 Traceback (most recent call last)
/tmp/ipykernel_32291/2973311999.py in <module>
----> 1 create_objection('c1',{'t':1},{'tt':2,'ttt':'3'})

TypeError: create_objection() takes 2 positional arguments but 3 were given

And I would like to get:

{'name': 'c1', 'position': {'t': 1}, 'extra_info': [{'whatever':[3453,3453]},{'whatever2':[34,34]}]}

How to proceed?

Post the actual whole stack-trace. The problem is most likely spelled out there. The problem is most probably because you've given the function too many positional arguments. the `**kwargs` argument means that it accepts any keyword-elements. — Hampus Larsson, Nov 09 '21 at 17:17
As said, kwargs is for arguments of type `keyword=value`. It looks like you are using a dictionary as a positional arg. — Seth Faulkner, Nov 09 '21 at 17:21
d = {'t':1, 'whatever':[3453,3453],'whatever2':[34,34]} def create_objection(*arg, **kwargs): pass create_objection('c', d) — hd1, Nov 09 '21 at 17:22

score 1 · Accepted Answer · answered Nov 09 '21 at 17:41

What is happening here is that you've defined a function that only has two positional arguments, and you're trying to give it 3, just as the error-message is telling you.

If we look at your code, then it doesn't look like you're trying to use keyword-arguments either so the **kwargs argument doesn't get used.

With just a minor change to your code we can get the result you want:

def create_objection(name, position, *args):
    dicct = {'name': name,
             'position': position}
    if args:
        dicct["extra_info"] = args
    return dicct

x = create_objection('c1', {'t': 1})
z = create_objection('c1', {'t': 1}, {'whatever': [3453, 3453]}, {'whatever2': [34, 34]})

print(x)
print(z)

Output:

{'name': 'c1', 'position': {'t': 1}}
{'name': 'c1', 'position': {'t': 1}, 'extra_info': ({'whatever': [3453, 3453]}, {'whatever2': [34, 34]})}

If you also want to include other keyword-arguments, then you can just do another loop over that variable like so:

def create_objection(name, position, *args, **kwargs):
    dicct = {'name': name,
             'position': position}
    if args:
        dicct["extra_info"] = args
    for key, value in kwargs.items():
        dicct[key] = value
    return dicct

y = create_objection('c1', {'t': 1}, {'whatever': [3453, 3453]}, thisisakeyword="totally a keyword!")
print(y)

Output:

{'name': 'c1', 'position': {'t': 1}, 'extra_info': ({'whatever': [3453, 3453]},), 'thisisakeyword': 'totally a keyword!'}

hd1 · Answer 2 · 2021-11-09T18:08:03.877

0

Try:

def create_objection(*args, **kwargs):
   dicct = {'name': args[0], 'position': args[1]}
   if not kwargs:
       print(len(kwargs))
       dicct.update{{'extra_info': kwargs})
   return dicct

Ignore the above, leaving that for the next lot here, but OP has to change the method to look like:

def create_objection(name=None, position=None, **kwargs):
   dicct = {'name': name, 'position': position}
   if not kwargs:
       print(len(kwargs))
       dicct.update{{'extra_info': kwargs})
   return dicct

edited Nov 09 '21 at 18:08

answered Nov 09 '21 at 17:25

hd1

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could this approach be expanded to have positional arguments, *args AND **kwargs?? – JFerro Nov 09 '21 at 17:28
*args is a list, **kwargs is a dict. As this solves your immediate problem, use it and post another question for your next issue – hd1 Nov 09 '21 at 17:29
the down side of this is that I can not call the method with objection=create_objection(name='XY', position='pos3') – JFerro Nov 09 '21 at 17:36
See the text I appended to my answer – hd1 Nov 09 '21 at 18:08

score 0 · Answer 3 · answered Nov 09 '21 at 17:26

0

Here is a similar issue

It looks like you need to unpack your dictionary when calling your function.

create_objection('c1',{'t':1},**{'whatever':[3453,3453]},{'whatever2':[34,34]})

Note the **

answered Nov 09 '21 at 17:26

Seth Faulkner

461
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Optionally passing an extra dictionary to a method / function

3 Answers3