Are Python functions objects?

Yes, Python functions are full objects. Python creates function objects when you use a def statement or a lambda expression. Like any other object, functions can be assigned to variables, passed as arguments, returned from other functions, and even have custom attributes.

Functions Have a Type and Support Attributes

Since functions are objects, they have a type (function) and you can assign custom attributes to them ?

Example

def foo():
    pass

foo.score = 20

print(type(foo))
print(foo.score)
print(type(lambda x: x))

The output of the above code is ?

<class 'function'>
20
<class 'function'>

Assigning Functions to Variables

We can assign a function to a variable just like we can assign an integer, string, or list to a variable ?

Example

def greet(name):
    print("Hello, " + name + "!")

hello = greet
hello("John")

The output of the above code is ?

Hello, John!

Here, we assign the function greet to a variable called hello and call it using that variable. Both greet and hello now reference the same function object.

Passing Functions as Arguments

We can pass a function as an argument to another function ?

Example

def add(x, y):
    return x + y

def multiply(x, y):
    return x * y

def apply(func, x, y):
    return func(x, y)

result = apply(add, 2, 3)
print(result)

The output of the above code is ?

5

Storing Functions in Data Structures

Functions can be stored as values in data structures like dictionaries ?

Example

def say_hello():
    return "Hello!"

def say_goodbye():
    return "Goodbye!"

messages = {
    "hello": say_hello,
    "goodbye": say_goodbye
}

print(messages["hello"]())
print(messages["goodbye"]())

The output of the above code is ?

Hello!
Goodbye!

Nested Functions (Closures)

Functions can be defined inside other functions and returned as values. This pattern is commonly known as a closure ?

Example

def outer_function():
    def inner_function(x, y):
        return x * y
    return inner_function

product_func = outer_function()
result = product_func(3, 5)
print(result)

The output of the above code is ?

15

Applying a Function to a List

Functions can be passed to other functions that iterate over collections, similar to the built-in map() function ?

Example

def apply_to_list(func, lst):
    result = []
    for element in lst:
        result.append(func(element))
    return result

def square(x):
    return x ** 2

numbers = [1, 2, 3, 4, 5]
squared_numbers = apply_to_list(square, numbers)
print(squared_numbers)

The output of the above code is ?

[1, 4, 9, 16, 25]

Setting Custom Attributes on Functions

Since functions are objects, you can set and read custom attributes on them ?

Example

def add(x, y):
    return x + y

add.name = "Addition"

print(add(2, 3))
print(add.name)

The output of the above code is ?

5
Addition

Conclusion

Python functions are first-class objects. They can be assigned to variables, passed as arguments, returned from other functions, stored in data structures, and given custom attributes − making them extremely flexible and a core part of Python's design.