![]() ![]() ![]() We will use the static type checker mypy and see what Python has to say about our code. ![]() Let’s use the same code that we ran before using an intand str. There are several type checkers for Python. Even if Python does not use type hinting at all, it helps us to leverage it to use a more declarative approach while writing our code and also to provide a runtime validation using external libraries.There are multiple automated code document generators that use type hints when they generate the documentation for example if we are writing our own code libraries with lots of functions and classes and also the included comments. Type hints are often used for code documentation.One of the things is that it helps IDEs display context-sensitive help information such as not only the function parameters but also what the expected type is.However, there are some really good reasons to use type hints even if Python ignores them. Python has no problems multiplying an intwith str. In the example above, we saw that the code runs fine even if we pass a string value to it. Python interpreter has no problem compiling the code if there is a valid data type present in out type hints like int, str, dict, and so on. When we try to run the code, it runs fine with no issues. Type Hinting tells us to pass in int values, yet we are passing a str. However, what if we try to pass an integer and a string? So according to it, we should be passing two integer values to our code and that would work fine. Python would have been just fine even if we do not put any type hints that we specified saying that num1 and num2 should be integers. This function is taking two arguments num1 and num2, that’s what Python sees when it’s going to run the code. We can note that the arguments have a semicolon with a data type assigned to them (num1: int, num2: int) It’s the good old normal function but the syntax here is a bit different. In the function declared above, we are assigning built-in data types to the arguments. Let’s go through an example and get an overview by assigning type hints to a function. The type hints do get compiled along with the rest of the code but they do not affect how Python executes your code. Now, the thing with type hints is that it does not modify how Python itself runs. They can be used by third-party tools such as type checkers, IDEs, linters, etc.Īlso read: The Magic Methods in Python Type Checking, Type Hints, and Code CompilationĪt first, we had some external third-party libraries for example the static type checker like mypy that started doing type hinting, and a lot of those ideas from mypy were actually brought into the canonical Python itself and integrated directly into Python. However, the Python runtime does not enforce function and variable type annotations. This helps to avoid bugs but at the same time makes the code more verbose. This addition to the Python language helped structure our code and make it feel more like a statically typed language. Starting from Python 3.5 there was an introduction of something called type hints in PEP 484 and PEP 483. We also have statically typed languages like Java, C, or C++, where we need to declare the variable type at the time of declaration and the variable types are known at compile time. Python interpreter assigns the type for variables at the runtime based on the variable’s value at that time. We don’t have to explicitly mention the data types for the declared variables or functions. ![]()
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