Call a function inside of a function inside of a class in Python

Question

So I'm having a problem with a larger piece of code where I'm getting an error message when I'm calling a function inside of another function that is inside of a class. In the code:

#Test program to solve problems. 

class Foo(object):
    def __init__(self, number):
        self.number = number

    def run(self):
        print "I will now square your number"
        print "Your number squared is: "
        print self.calculate()

    #This squares the number
        def calculate(self):
            return self.number**2


if __name__ == "__main__":
    test = Foo(input("Choose a number: "))
    print test.run()

I raise an "AttributeError: Foohas no attribute calculate", but I don't understand why? Am I calling calculate wrong to throw this error?

EDIT

So I know that if I change the indentation or calculate it works, but I wanna know is there anyway to get it working as it currently is with calculate indented in run or do python classes not work that way.

Your indent level is off when you are defining calculate.

Tadgh
– Tadgh

2014-08-13 18:48:00 +00:00
Commented Aug 13, 2014 at 18:48 — Tadgh
– Tadgh, Commented Aug 13, 2014 at 18:48

Community · Accepted Answer · 2017-05-23 10:26:18Z

5

Updated after question edit:

Check out this link that shows how to make a "closure" https://stackoverflow.com/a/4831750/2459730

It's what you described as a function inside of a function.

def run(self):
    def calculate(self): # <------ Need to declare the function before calling
        return self.number**2

    print "I will now square your number"
    print "Your number squared is: "
    print self.calculate() # <---- Call after the function is declared

Before question edit: Your calculate function isn't indented properly.

def run(self):
    print "I will now square your number"
    print "Your number squared is: "
    print self.calculate()

#This squares the number
def calculate(self): # <----- Proper indentation
    return self.number**2 # <------ Proper indentation

The calculate function should have the same indentation level as the run function.

edited May 23, 2017 at 10:26

CommunityBot

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answered Aug 13, 2014 at 18:48

Andrew_CS

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5 Comments

Jose Magana Over a year ago

Doesn't he want the function inside the function?

Andrew_CS Over a year ago

No, he just wants to call it from another function inside of the same class.

Flameancer Over a year ago

No I actually want calculate() inside run(). In my actual the body of calculate is dependent on run.

Andrew_CS Over a year ago

@Flameancer OK well your question said otherwise, if that's the case then you should edit your question to be more clear.

Flameancer Over a year ago

@Andrew_CS thanks to pointing me to closure. This was exactly what I was looking for. This code and my actual code works perfect now.

Tadgh · Accepted Answer · 2014-08-13 18:49:06Z

3

Indentation level is off. You are defining calculate INSIDE of the run function instead of in the class.

class Foo(object):
    def __init__(self, number):
        self.number = number

    def run(self):
        print "I will now square your number"
        print "Your number squared is: "
        print self.calculate()

    #This squares the number
    def calculate(self): #NOTE THE INDENTATION DIFFERENCE
        return self.number**2


if __name__ == "__main__":
    test = Foo(input("Choose a number: "))
    print test.run()

answered Aug 13, 2014 at 18:49

Tadgh

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Comments

go1dshtein · Accepted Answer · 2014-08-13 21:28:53Z

1

Seems you call function before it is defined. I think closure should help you:

def run(self):
    print "I will now square your number"
    print "Your number squared is: "

    def calculate():
        return self.number**2

    print calculate()

answered Aug 13, 2014 at 21:28

go1dshtein

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Comments

MANGESH DESHPANDE · Accepted Answer · 2021-05-12 06:57:05Z

1

When you define a function inside a function then there is not need to use 'self' in inner function and call function after defining it. so you can write the code as,

class Foo(object):
    def __init__(self, number):
        self.number = number

    def run(self):
        #This squares the number
        def calculate():
            return self.number**2

        print "I will now square your number"
        print "Your number squared is: "
        print calculate()

if __name__ == "__main__":
    test = Foo(int(input("Choose a number: ")))
    print test.run()

answered May 12, 2021 at 6:57

MANGESH DESHPANDE

111 bronze badge

Comments

Jaywu Jun · Accepted Answer · 2021-12-13 20:21:22Z

0

The problem is just that you can't do that. It may seem tempting because you can outside of a class and it makes your code a littler cleaner, but within a class, you can't do it.

answered Dec 13, 2021 at 20:21

Jaywu Jun

1

1 Comment

holydragon Over a year ago

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