Rust 中的依赖说明符 (PEP 508)

一个用于 Python 依赖说明符 的库，更广为人知的是 PEP 508.

用法

Rust 中

use std::str::FromStr;
use pep508_rs::Requirement;

let marker = r#"requests [security,tests] >= 2.8.1, == 2.8.* ; python_version > "3.8""#;
let dependency_specification = Requirement::from_str(marker).unwrap();
assert_eq!(dependency_specification.name, "requests");
assert_eq!(dependency_specification.extras, Some(vec!["security".to_string(), "tests".to_string()]));

Python 中

from pep508_rs import Requirement

requests = Requirement(
    'requests [security,tests] >= 2.8.1, == 2.8.* ; python_version > "3.8"'
)
assert requests.name == "requests"
assert requests.extras == ["security", "tests"]
assert [str(i) for i in requests.version_or_url] == [">= 2.8.1", "== 2.8.*"]

Python 绑定是用 maturin 构建的，但您也可以使用正常的 pip install .

Version 和 VersionSpecifier 从 pep440_rs 中重新导出，以避免类型不匹配。

标记

标记允许您只在特定环境中安装依赖项（Python 版本、操作系统、架构等）或当特定功能被激活时安装依赖项。例如，您可以说 importlib-metadata ; python_version < "3.8" 或 itsdangerous (>=1.1.0) ; extra == 'security'。不幸的是，标记语法有一些疏漏（例如 https://github.com/pypa/packaging.python.org/pull/1181）并且比较的设计（PEP 440 比较与字典序回退）导致了令人困惑的结果。此实现试图仔细验证一切，并在遇到不正确语义的比较时发出警告。

在 Python 中，警告默认发送到正常的 Python 日志基础设施

from pep508_rs import Requirement, MarkerEnvironment

env = MarkerEnvironment.current()
assert not Requirement("numpy; extra == 'science'").evaluate_markers(env, [])
assert Requirement("numpy; extra == 'science'").evaluate_markers(env, ["science"])
assert not Requirement(
    "numpy; extra == 'science' and extra == 'arrays'"
).evaluate_markers(env, ["science"])
assert Requirement(
    "numpy; extra == 'science' or extra == 'arrays'"
).evaluate_markers(env, ["science"])

from pep508_rs import Requirement, MarkerEnvironment

env = MarkerEnvironment.current()
Requirement("numpy; python_version >= '3.9.'").evaluate_markers(env, [])
# This will log: 
# "Expected PEP 440 version to compare with python_version, found '3.9.', "
# "evaluating to false: Version `3.9.` doesn't match PEP 440 rules"