Dynamic typing is a feature in programming languages where the type of a variable is determined at runtime rather than at compile-time. This means you don’t have to explicitly declare a variable’s data type (like int, string, or float) when you create it. Instead, the language’s interpreter automatically assigns a type based on the value you give it.

Dynamic vs. Static Typing

To truly understand dynamic typing, it helps to compare it with its counterpart, static typing.

• Static Typing: In statically typed languages like Java, C++, or C#, you must declare a variable’s type before you use it. For example, you’d write int myNumber = 10;. Once declared as an int, that variable can only ever hold integer values. If you try to assign a string to it later, like myNumber = "hello";, the program won’t even compile because the compiler catches this type mismatch before the code runs.
• Dynamic Typing: In dynamically typed languages like Python, JavaScript, and Ruby, you simply write myVariable = 10. The interpreter sees the number 10 and automatically understands that myVariable is an integer. You can then later reassign that same variable to a different type, like myVariable = "hello", and the program will run without a problem. The type of the variable is flexible and can change throughout the program’s execution.

Advantages and Disadvantages

Advantages 👍

• Flexibility and Speed: Dynamic typing allows for rapid development and prototyping. You don’t have to worry about strict type declarations, which means you can write and test code faster. This is particularly useful for scripting, web development, and smaller projects where the data types might be unknown or frequently change.
• Concise Code: Code written in dynamically typed languages is often less verbose because you don’t need to write out type declarations for every variable, function parameter, or return value.

Disadvantages 👎

• Runtime Errors: The biggest drawback is that type-related errors are only caught when the code runs. A type mismatch that would be a compile-time error in a statically typed language can go unnoticed in a dynamically typed one until that specific line of code is executed. This can lead to unexpected bugs and crashes in production.
• Performance Overhead: Because the interpreter has to perform type checking at runtime, dynamically typed languages can be slower than statically typed languages, which perform these checks once at compile-time.
• Reduced Readability: In large, complex codebases, the lack of explicit type information can make the code harder to read and understand. It may not be immediately clear what type of data a variable or function is expected to handle, which can complicate maintenance and collaboration.