Google Open-Sources the Common Expression Language for Python

"CEL has become a prevalent technology for applications like policy enforcement, data validation, and dynamic configuration. This release provides an officially maintained implementation, making it easier to use CEL consistently across infrastructure and applications. As a result, Python developers now have a first-party CEL runtime instead of relying on community-supported libraries."

"The CEL team has chosen to develop CEL-expr-python by wrapping our official C++ implementation to ensure maximum consistency with CEL semantics while enabling Python users to extend and enrich the experience on top of this production-ready core in Python directly. Another advantage of wrapping the official C++ implementation is that any future improvements to the C++ core, including new features and optimizations, will automatically be inherited by CEL-expr-python."

"I have been using ad-hoc AST evaluators for feature flags and they are painful to maintain - the expressions drift from what the runtime actually supports. Having a proper type-checked compile step would catch so many issues upfront."

Google has released CEL-expr-python, an officially maintained Python implementation of the Common Expression Language (CEL), a non-Turing complete embedded language designed for simplicity, speed, safety, and portability. CEL has become prevalent in policy enforcement, data validation, and dynamic configuration applications. The implementation wraps Google's official C++ core to ensure semantic consistency while allowing Python-specific extensions. This approach guarantees that future C++ improvements automatically benefit the Python version. Python developers now have access to a first-party CEL runtime instead of relying on community-supported alternatives, enabling consistent CEL usage across infrastructure and applications.

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