What is first class object in python?

In python, functions are first class objects in python.

Advantages of first class objects:

• We can treat functions like other normal objects like int, string, list etc
• We can pass functions as another function arguments, return a function in another function and assign a function to another variable
• Define a function within a function (Inner functions)
• This first class object plays a key role in python for decorator design pattern.

Examples:

# Simple function for adding two numbers
def add_num(num1, num2):
    return num1 + num2
# Passing function as a first argument
def add_values(fun, arg1, arg2):
    result = fun(arg1, arg2)
    return result
# Simple function for adding two numbers
def add_num(num1, num2):
    return num1 + num2

# Passing function as a first argument
def add_values(fun, arg1, arg2):
    result = fun(arg1, arg2)
    return result
# Simple function for adding two numbers
def add_num(num1, num2):
    return num1 + num2

# Passing function as a first argument
def add_values(fun, arg1, arg2):
    result = fun(arg1, arg2)
    return result

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• Assigning function name to the variable:

fun = add_num
fun = add_num
fun = add_num

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• Passing function as a parameter

two_num_sum = add_values(fun, 5, 8))
two_num_sum = add_values(fun, 5, 8))
two_num_sum = add_values(fun, 5, 8))

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原文链接：What is first class object in python?