Missing Positional Arguments Python (Directing to a function)

Question

I'm trying to figure out how to direct a function to a function. What I'm trying to do is answer a prompt question y/n that would run a certain function. When I input y, it will run through both functions instead of only function 1.

Thanks!

def company_type(question, public_company, private_company):
    print("Is the target company public on NYSE or NASDAQ?")
    prompt = f'{question} (y/n)'
    ans = input(prompt)
    if ans == 'y':
        return (public_company)
    if ans == 'n':
        print("Please enter financial infomation manually.")
        return (private_company)
company_type("public_company", "private_company", 1)

# function 1 
def public_company(): 
    return (print("Success 1"))
public_company()

# function 2
def private_company():
   return (print("Success 2"))
private_company()

What do you expect `function(public_company)` to do? You haven't defined `function` and it's not built in to Python. Why not just call `public_company` or `private_company`? — kindall, Nov 09 '21 at 05:53
Does this answer your question? [Creating a new function as return in python function?](https://stackoverflow.com/questions/12738031/creating-a-new-function-as-return-in-python-function) — AJ Biffl, Nov 09 '21 at 05:54
Or this? [How do I write a function that returns another function?](https://stackoverflow.com/questions/14261474/how-do-i-write-a-function-that-returns-another-function/14271106) — AJ Biffl, Nov 09 '21 at 05:55

score 1 · Answer 1 · edited Nov 09 '21 at 07:36

1

You don't really want to return a function. You just want one function to call another function. That's done like this:

# function 1 
def public_company(): 
    return print("Success 1")

# function 2
def private_company():
    return print("Success 2")

def company_type(question, public_company, private_company):
    print("Is the target company public on NYSE or NASDAQ?")
    prompt = f'{question} (y/n)'
    ans = input(prompt)
    if ans == 'y':
        return public_company()
    else:
        print("Please enter financial information manually.")
        return private_company()

company_type("some question", public_company, private_company)

And please note that return statements in Python do not use an extra set of parentheses. That's a C idiom.

edited Nov 09 '21 at 07:36

AJ Biffl

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answered Nov 09 '21 at 05:57

Tim Roberts

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why are you returning `public_company()` or `private_company()`? those return `print` statements, which evaluate to `None` – AJ Biffl Nov 09 '21 at 06:00
Presumably, those are placeholders, to be filled in with something useful once he gets the mechanics figured out. – Tim Roberts Nov 09 '21 at 06:02
Thank you so much Tim! And yes the public and private company are place holders. – Trevor Seibert Nov 09 '21 at 20:02

score 1 · Answer 2 · answered Nov 09 '21 at 06:15

You can absolutely return a function to be used later - this is the essence of functional programming, and the reason to have functions as first class objects in python ~ Guido Van Rossum.

The important thing is to remember that parens mean a function call, whereas no parens mean the function object.

def public_company():
    print("we do what public companies do")

def private_company():
   print("we do what private companies do")


def choose_company():
    ans = input("Is the target company public?")
    if ans == 'y':
        return public_company   # no parens
    else:
        return private_company  # no parens


if __name__ == '__main__':
    # assign the returned function to selected_company
    selected_company = choose_company()

    # calling selected_company() will call the selected function
    selected_company()   # use parens, this is a function call!

score 0 · Answer 3 · answered Nov 09 '21 at 05:59

Errors:-

function is not a keyword.
We can call a function by:- <function_name>().

# function 1 
def public_company(): 
    print("Success")
    
# function 2
def private_company():
    print("Success")

def company_type():
    print("Is the target company public on NYSE or NASDAQ?")
    prompt = 'Is your company a public company? (y/n)'
    ans = input(prompt)
    if ans == 'y':
        public_company()
    if ans == 'n':
        print("Please enter financial information manually.")
        private_company()
company_type()

Missing Positional Arguments Python (Directing to a function)

3 Answers3

Errors:-