Returning a function from a function means that a function is created and returned as output of another function. This is possible in Python because functions are first-class objects, which means they can be passed around just like any other object such as integers, strings, or lists.

## Return Function in Python

In the following examples, Python functions are utilized to return other functions, allowing for dynamic behavior based on input parameters.

### Example 1: Basic Usage of Function Return

Consider `function1`

, which returns another function, `function2`

. This inner function `function2`

multiplies its argument by a specified value, `a`

. When `function1(5)`

is called, it returns `function2`

with `a`

set to `5`

. The resulting function is assigned to the variable `multiply_by_5`

. Subsequently, calling `multiply_by_5(3)`

outputs `15`

.

```
def function1(a):
def function2(b):
return a * b
return function2
multiply_by_5 = function1(5)
result = multiply_by_5(3)
print(result) # Output: 15
```

### Example 2: Conditional Return of Functions

In this scenario, `function3`

determines which function to return based on the value of the `operation`

parameter. It contains two inner functions: `add_numbers`

and `multiply_numbers`

, respectively performing addition and multiplication operations.

By passing either `add`

or `multiply`

to `function3`

, it returns the corresponding inner function. For instance, if `operation_type`

is set to `add`

, the `add_numbers`

function is assigned to the `math_function`

variable. Invoking `math_function(3, 5)`

will add the two numbers, resulting in an output of `8`

.

```
def function3(operation):
def add_numbers(a, b):
return a + b
def multiply_numbers(a, b):
return a * b
if operation == "add":
return add_numbers
elif operation == "multiply":
return multiply_numbers
operation_type = "add"
math_function = function3(operation_type)
result = math_function(3, 5)
print(result) # Output: 8
```

In summary, these examples illustrate how Python functions can be utilized to return other functions dynamically, providing versatility in handling operations based on input conditions.

## Exploring the Concept of Nested Functions and Returning Functions

In Python, functions can be nested, which means you can define one function inside another function. You can also return a function from another function in Python. This concept of nested functions and returning functions allows for more flexibility and is a powerful tool in programming.

### Example 1: Returning a Function from a Function

```
def create_adder(num):
def adder(x):
return num + x
return adder
add5 = create_adder(5)
print(add5(3)) # Output: 8
```

In this example, we define a function `create_adder`

that takes a parameter `num`

. Inside `create_adder`

, we define another function `adder`

that takes a parameter `x`

and returns the sum of `num`

and `x`

. Finally, `create_adder`

returns `adder`

.

We then create a new function `add5`

by calling `create_adder(5)`

. This means that `add5`

is now a reference to `adder`

with `num`

set to 5. When we call `add5(3)`

, we pass the parameter `x`

as `3`

, which results in the output `8`

.

### Example 2: Nested Functions

```
def outer_function(num):
def inner_function(x):
return num + x
return inner_function
add3 = outer_function(3)
add5 = outer_function(5)
print(add3(10)) # Output: 13
print(add5(10)) # Output: 15
```

In this example, we define a function `outer_function`

that takes a parameter `num`

. Inside `outer_function`

, we define another function `inner_function`

that takes a parameter `x`

and returns the sum of `num`

and `x`

. Finally, `outer_function`

returns `inner_function`

.

We then create two new functions `add3`

and `add5`

by calling `outer_function(3)`

and `outer_function(5)`

respectively. This means that `add3`

is now a reference to `inner_function`

with `num`

set to 3, and `add5`

is a reference to `inner_function`

with `num`

set to 5. When we call `add3(10)`

and `add5(10)`

, we pass the parameter `x`

as `10`

, which results in the output `13`

and `15`

respectively.

## Understanding the Advantages of Returning a Function from Another Function

One of the significant benefits of returning a function from another function in Python is that it provides flexibility. By returning a function, the programmer can create a more specific and customized function based on the inputs passed to the original function. It also allows for efficient code reuse.

Another advantage of returning a function from another function is that it can simplify code complexity, leading to a more readable code structure. The code becomes more organized and understandable, thus enhancing its maintenance and debugging processes.

Here are two examples of returning a function from a function in Python:

### Example 1: Returning a Function That Multiplies Any Number By a Given Factor:

```
def multiply(factor):
def inner(num):
return num * factor
return inner
double = multiply(2)
triple = multiply(3)
print(double(5)) #output: 10
print(triple(5)) #output: 15
```

By calling `multiply(2)`

and `multiply(3)`

, we create two new functions `double`

and `triple`

, respectively, that can be used to multiply any number by `2`

or `3`

.

### Example 2: Returning a Function That Performs Mathematical Operations:

```
def operate(operation):
def inner(num1, num2):
if operation == 'add':
return num1 + num2
elif operation == 'subtract':
return num1 - num2
elif operation == 'multiply':
return num1 * num2
elif operation == 'divide':
return num1 / num2
return inner
add_func = operate('add')
subtract_func = operate('subtract')
print(add_func(10, 5)) #output: 15
print(subtract_func(10, 5)) #output: 5
```

By calling `operate('add')`

and `operate('subtract')`

, we create two new functions `add_func`

and `subtract_func`

, respectively, that can be used to perform addition and subtraction operations on any two numbers.

## Understanding the Different Ways of Defining and Returning Functions in Python

Returning a function from a function can be useful in situations where we need to create functions dynamically based on certain conditions.

```
def create_adder(num):
def adder(x):
return x + num
return adder
add5 = create_adder(5)
print(add5(10)) # Output: 15
```

In this example, we define a function called `create_adder`

that takes a `num`

parameter. Within the `create_adder`

function, we define another function called `adder`

that takes an `x`

parameter and returns the sum of `num`

and `x`

. Finally, we return the `adder`

function as an output.

We then assign the output of `create_adder(5)`

to a variable called `add5`

. This means that `add5`

is now a function that takes a parameter `x`

and returns the sum of `5`

and `x`

. When we call `add5(10)`

, it returns `15`

.

## Exploring the Use Arguments in Returned Functions

```
def power(base):
def exponent(exp):
return base ** exp
return exponent
square = power(2)
cube = power(3)
print(square(5)) # Output: 25
print(cube(3)) # Output: 27
```

In this example, a nested function `exponent`

is defined inside the `power`

function. The `exponent`

function calculates a number raised to a power. The `power`

function returns the `exponent`

function. Two variables `square`

and `cube`

are assigned by calling the `power`

function with different base values. The final two print statements call `square`

and `cube`

with different exponent values.

```
def operation(operator):
def calculate(num1, num2):
if operator == '+':
return num1 + num2
elif operator == '-':
return num1 - num2
elif operator == '*':
return num1 * num2
elif operator == '/':
return num1 / num2
else:
return "Invalid operator"
return calculate
addition = operation('+')
subtraction = operation('-')
multiplication = operation('*')
division = operation('/')
print(addition(5, 3)) # Output: 8
print(subtraction(5, 3)) # Output: 2
print(multiplication(5, 3)) # Output: 15
print(division(5, 3)) # Output: 1.6666666666666667
print(operation('%')(5, 3)) # Output: Invalid operator
```

In this example, the `operation`

function takes an `operator`

parameter and returns the `calculate`

function. The `calculate`

function performs the arithmetic operation specified by the `operator`

parameter on two number arguments. Four variables `addition`

, `subtraction`

, `multiplication`

, and `division`

are assigned by calling the `operation`

function with different operator values. The final print statement shows what occurs when an invalid operator is used as an argument.

### Contribute with us!

Do not hesitate to contribute to Python tutorials on GitHub: create a fork, update content and issue a pull request.