cel-expr-python

What it is and what it does

cel-expr-python is a Python binding to the CEL C++ runtime, enabling you to parse, compile, and evaluate CEL expressions—a Google-designed language for policy evaluation and access control. It lets you define typed variables, compile expressions once for reuse, and evaluate them efficiently against different data sets. The package supports protobuf messages as first-class values, custom Python functions, optional type checking at compile time, and memory-efficient evaluation via shared arenas and activations.

You typically use it to build policy engines, authorization systems, or rule evaluators where expressions need to be safe, sandboxed, and fast. The wrapper handles the C++ complexity, exposing a straightforward Python API for environment setup, expression compilation, and evaluation with optional configuration for descriptor pools, containers, and extensions.

Use it for

• Authorization and access control: evaluate policies like 'user.role in ["admin"] && request.resource == "sensitive_data"'.
• Rule engines in microservices: compile and cache expressions once, then evaluate them across many requests with different variable bindings.
• Protobuf-based validation: check constraints on protobuf message fields within CEL expressions.
• Custom business logic: define domain-specific functions and reuse them across multiple compiled expressions.
• Memory-constrained evaluation: use Arena for batch evaluation to release temporary objects as a group.

Worth the install?

AI-flagged interpretation of the facts on this page. Verify before relying on it.

Install

cel-expr-python on PyPI

Before you install

Medium install friction due to compiled wheels for multiple Python versions (3.11–3.14) and platforms (macOS, Linux, Windows). Active maintenance with a recent release (50 days ago) and an active repository.

Requires Python 3.11 or later; precompiled wheels available for macOS (Intel and ARM), Linux (x86_64 and aarch64), and Windows.

License in practice

Apache-2.0 permissive license allows commercial and private use with minimal restrictions; you must include a copy of the license and state significant changes.

Quickstart

pip install cel-expr-python

from cel_expr_python import cel

cel_env = cel.NewEnv(variables={"x": cel.Type.INT, "y": cel.Type.INT})
expr = cel_env.compile("x + y > 10")
result = expr.eval(data={"x": 7, "y": 4})
print(result.value())  # True

Package facts

Evidence: cel_expr_python-0.1.3-cp311-cp311-macosx_10_13_x86_64.whl; cel_expr_python-0.1.3-cp311-cp311-macosx_11_0_arm64.whl; cel_expr_python-0.1.3-cp311-cp311-manylinux_2_26_aarch64.manylinux_2_28_aarch64.whl; cel_expr_python-0.1.3-cp311-cp311-manylinux_2_27_x86_64.manylinux_2_28_x86_64.whl; cel_expr_python-0.1.3-cp311-cp311-win_amd64.whl; cel_expr_python-0.1.3-cp312-cp312-macosx_10_13_x86_64.whl; cel_expr_python-0.1.3-cp312-cp312-macosx_11_0_arm64.whl; cel_expr_python-0.1.3-cp312-cp312-manylinux_2_26_aarch64.manylinux_2_28_aarch64.whl; cel_expr_python-0.1.3-cp312-cp312-manylinux_2_27_x86_64.manylinux_2_28_x86_64.whl; cel_expr_python-0.1.3-cp312-cp312-win_amd64.whl; cel_expr_python-0.1.3-cp313-cp313-macosx_10_13_x86_64.whl; cel_expr_python-0.1.3-cp313-cp313-macosx_11_0_arm64.whl; cel_expr_python-0.1.3-cp313-cp313-manylinux_2_26_aarch64.manylinux_2_28_aarch64.whl; cel_expr_python-0.1.3-cp313-cp313-manylinux_2_27_x86_64.manylinux_2_28_x86_64.whl; cel_expr_python-0.1.3-cp313-cp313-win_amd64.whl; cel_expr_python-0.1.3-cp314-cp314-macosx_10_15_x86_64.whl; cel_expr_python-0.1.3-cp314-cp314-macosx_11_0_arm64.whl; cel_expr_python-0.1.3-cp314-cp314-manylinux_2_26_aarch64.manylinux_2_28_aarch64.whl; cel_expr_python-0.1.3-cp314-cp314-manylinux_2_27_x86_64.manylinux_2_28_x86_64.whl; cel_expr_python-0.1.3-cp314-cp314-win_amd64.whl

Tags

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