What is Type Hinting?

Python is a dynamically-typed language, meaning that variables are not assigned a data type when they are declared. This allows for flexibility and ease of use, but it can also allow for bugs and errors related to data types that can be difficult to catch. Python Type Hinting is a solution to this problem that has been introduced in Python 3.5.

Type Hinting allows developers to specify the data type of a variable, function parameter, or function return type in their code. This information is not enforced by the interpreter, but it can be used by analysis tools and IDEs to provide better code completion, error checking, and documentation.

How to use it?

To use Type Hinting in Python, you simply add a colon and the data type after the variable or function parameter name, like this:

def my_func(a: str, b: int) -> dict:
    return {'string_val': a, 'int_val': b}

In this example, the function my_func takes a string and an integer as parameters and returns a dictionary. The Type Hints make it clear what types of data the function expects and what type of data it will return.

Type Hints can also be used with class attributes, like this:

class Dog:
    name: str
    breed: str
    age: int

    def __init__(self, name: str, breed: str, age: int):
        self.name = name
        self.breed = breed
        self.age = age

In this example, the Dog class has three attributes, name breed and age, all of which are Type Hinted. The __init__ method takes two parameters, both of which are Type Hinted as well.

Type Hints can also be used with lists, dictionaries, and other data structures. Here is an example of a function that takes a list of integers and returns a dictionary that counts the occurrences of each integer in the list:

from typing import List, Dict

def count_numbers(numbers: List[int]) -> Dict[int, int]:
    counts = {}
    for number in numbers:
        if number in counts:
            counts[number] += 1
        else:
            counts[number] = 1
    return counts

In this example, the count_numbers function takes a list of integers and returns a dictionary where the keys are the integers in the list and the values are the number of times each integer appears.

Type Hints can be especially helpful in large code bases where it can be difficult to keep track of variable types. By using Type Hints, you can make your code more readable and easier to maintain, while also catching potential bugs and errors before they become a problem.

Python Type Hinting is a powerful tool that can help developers write better, more robust code. By providing information about the data types of variables, function parameters, and function return values, Type Hints can make code more readable and maintainable while also proactively catching bugs and errors. If you haven't already started using Type Hints in your code, I'd recommend considering using them.