Python store function in variable with arguments

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In this article, we are going to see how to assign a function to a variable in Python. In Python, we can assign a function to a variable. And using that variable we can call the function as many as times we want. Thereby, increasing code reusability. 

Implementation

Simply assign a function to the desired variable but without () i.e. just with the name of the function. If the variable is assigned with function along with the brackets (), None will be returned.

Syntax:

def func():
{
..
}

var=func

var()
var()

Example:

Python3

def a():

  print("GFG")

var=a

var()

Output: 

GFG

The following programs will help you understand better:

Example 1: 

Python3

x = 123

def sum():

    x = 98

    print(x)

    print(globals()['x'])

print(x)

z = sum

z()

z()

Output:

123
98
123
98
123

Example 2: parameterized function

Python3

def even_num(a):

    if a % 2 == 0:

        print("even number")

    else:

        print("odd number")

z = even_num

z(67)

z(10)

z(7)

Output:

odd number
even number
odd number

Example 3:

Python3

def multiply_num(a):

    b = 40

    r = a*b

    return r

z = multiply_num

print(z(6))

print(z(10))

print(z(100))

Output:

240
400
4000

redyugi 5 Junior Poster in Training

Not unless you are going to use "exec()" and people advise against that.

The second way is a good way.

class Test:
    def Testing(self):
        # Run function

x = Test()
x.Testing()

bumsfeld 413 Nearly a Posting Virtuoso

Simply store the reference to the function in the variable. Here is example:

def one():
    print("hello from function one")

def two():
    print("hello from function two")

def three():
    print("hello from function three")

# stores the ref of function in variable
f1 = one
f2 = two
f3 = three
func_list = [f1, f2, f3]

for f in func_list:
    # show the function reference
    print(f)
    # call the function
    f()

"""my display -->

hello from function one

hello from function two

hello from function three
"""

redyugi 5 Junior Poster in Training

Simply store the reference to the function in the variable. Here is example:

def one():
    print("hello from function one")

def two():
    print("hello from function two")

def three():
    print("hello from function three")

# stores the ref of function in variable
f1 = one
f2 = two
f3 = three
func_list = [f1, f2, f3]

for f in func_list:
    # show the function reference
    print(f)
    # call the function
    f()

"""my display -->

hello from function one

hello from function two

hello from function three
"""

I never knew I could do that. I knew you could do it with a class instance but...thanks

12 Years Ago

Awesome. That solves a tonne of problems. Thanks. =)

4 Years Ago

I need help on my Python project. I am creating a guess the number game and I need to include a menu, collect statistics, and plot statistics results. I have already created the game, but I don't know how to include a menu, collect statistics, or plot the results. Please help!!

3 Years Ago

Hi,
I too have same functinality like you guys posted here...
it iis working fine when I pass arguments to defined functions.

going wrong if the function is specified with "self"

Ex:

class Anyclassname:
    def __init__ (self, a):
        self.a = a
    def one(self, dicti):
        print("hello from function one")
        print(self.a, dicti)

 ## Assume that instance is created  function is called refering eith instance

 for f in func_list:
     # show the function reference
     print(f)
     # call the function
     dicti = {'1': 'one'}
     f(dicti)

#throwing error as "Print the exception one() missing 1 required positional argument: 'dicti'"

Please help me with this...

3 Years Ago

Hi @Akshay_15,

Why not post your question as a new topic instead of commenting on an old post here ?

Edited 3 Years Ago by John_165

1 Year Ago

class Callback:
    def __init__(self, fun, *args, **kwargs):
        self.fun = fun
        self.args = args
        self.kwargs = kwargs

    def __call__(self):
        self.fun(*self.args, **self.kwargs)

def say(message):
    print(message)


if __name__ == "__main__":
    callback = Callback(say, message="Hello")
    callback()

This would be more general solution.

Edited 1 Year Ago by tomas_petricek