Beartype is a Python library that validates type annotations while a program is executing. Unlike conventional static type checkers, which examine source code without running it, Beartype can detect mismatches between declared types and the actual objects encountered during execution.
The library is intended for situations where runtime checking provides additional confidence, such as validating inputs from dynamically typed components or detecting incorrect return values during testing. It can be introduced into selected functions or applied across larger portions of an application.
Beartype concentrates on keeping the overhead of type checking low. Its checks complement conventional static analysis rather than replace it, particularly when a program interacts with untyped libraries, external data or other components whose behaviour cannot be fully determined ahead of time.
This is free and open source software.
Key Features
- Provides the @beartype decorator for checking annotated function parameters and return values during execution.
- Supports import hooks for applying type checking automatically across selected packages.
- Understands standard Python type annotations, including unions, generic containers and annotated types.
- Provides custom validators through typing.Annotated and the beartype.vale API.
- Offers procedural APIs for checking arbitrary objects against specified type hints.
- Generates detailed exceptions identifying values that violate their declared types.
- Supports configurable checking strategies for container elements, balancing performance against validation coverage.
- Generates specialised checking logic to reduce the overhead of repeated runtime validation.
Website: github.com/beartype/beartype
Support:
Developer: Beartype authors
License: MIT License
Beartype is written in Python. Learn Python with our recommended free books and free tutorials.
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