2 posts tagged with "runtime-validation"

Python is famous for being a "consenting adults" language. By default, type hints (like name: str) are just polite suggestions. If you pass an integer into a function expecting a string, Python will happily execute it-and probably crash three lines later.

In 2026, relying on "polite suggestions" isn't enough for production-grade code. To actually enforce type hinting, you have to move beyond the built-in typing module and use external guardians.

Typeguard is a lightweight yet powerful Python library that enforces type hints at runtime. Unlike static checkers (like MyPy or Pylance), which only check code before execution, Typeguard uses function decorators to ensure that function arguments and return values strictly adhere to their type annotations during execution. If a type mismatch occurs, Typeguard raises a TypeError, effectively making your type hints mandatory contracts.

This article explores various practical use cases and examples for deploying Typeguard.