How To Call A Nested Function Python

In this tutorial, we will discuss how to call a nested function in Python. A nested function (also known as an “inner function” or “subfunction”) is a function defined inside another function.

It is an efficient way to encapsulate a function for use within the outer function, and not exposing it to the global scope of your code.

Step 1: Define a nested function

First, let’s define a nested function. To do this, we will create an outer function and an inner function. Here’s an example:

The outer_function takes a single parameter x, and it contains the definition of the inner_function. The inner_function takes a parameter y and returns the square of y. The outer_function then calls the inner_function and stores its output in a variable called the result. Finally, the outer_function returns this result.

Step 2: Call the nested function

To call a nested function, simply call the outer function. In our example, we call the outer_function with argument 4, and it will subsequently call the nested inner_function to compute the result.

The output of the code above is:


Step 3: Accessing variables from the outer function

A nested function can access variables from its containing outer function. In this example, the nested function will use the variable from the outer function and multiply it by a given argument:

In this example, the outer_function accepts an argument x and returns the inner_function, which can now access the value of x directly. When we call outer(4), we are actually calling the inner_function with the argument y=4 and the value of x=10 from outer_function.

The output of the code above is:


Full code example

Here is the full code example used in this tutorial:

The output is:



In this tutorial, we have learned how to call a nested function in Python. We demonstrated how to define a nested function, call it using the outer function, and access variables from the outer function.

Nested functions can be very useful in organizing and encapsulating code, enhancing the readability and maintainability of your Python scripts.