From 1f733eef89de63d47dcdb03db3948478d436af4d Mon Sep 17 00:00:00 2001 From: zEpoch <48525863+zEpoch@users.noreply.github.com> Date: Thu, 1 Jul 2021 19:24:30 +0800 Subject: [PATCH] Update and rename sources/tech/20210625 Use Python to parse configuration files.md to translated/tech/20210625 Use Python to parse configuration files.md --- ...Use Python to parse configuration files.md | 205 ------------------ ...Use Python to parse configuration files.md | 205 ++++++++++++++++++ 2 files changed, 205 insertions(+), 205 deletions(-) delete mode 100644 sources/tech/20210625 Use Python to parse configuration files.md create mode 100644 translated/tech/20210625 Use Python to parse configuration files.md diff --git a/sources/tech/20210625 Use Python to parse configuration files.md b/sources/tech/20210625 Use Python to parse configuration files.md deleted file mode 100644 index eaf0c699cc..0000000000 --- a/sources/tech/20210625 Use Python to parse configuration files.md +++ /dev/null @@ -1,205 +0,0 @@ -[#]: subject: (Use Python to parse configuration files) -[#]: via: (https://opensource.com/article/21/6/parse-configuration-files-python) -[#]: author: (Moshe Zadka https://opensource.com/users/moshez) -[#]: collector: (lujun9972) -[#]: translator: (zepoch) -[#]: reviewer: ( ) -[#]: publisher: ( ) -[#]: url: ( ) - -Use Python to parse configuration files -====== -The first step is choosing a configuration format: INI, JSON, YAML, or -TOML. -![Python programming language logo with question marks][1] - -Sometimes, a program needs enough parameters that putting them all as command-line arguments or environment variables is not pleasant nor feasible. In those cases, you will want to use a configuration file. - -There are several popular formats for configuration files. Among them are the venerable (although occasionally under-defined) `INI` format, the popular but sometimes hard to write by hand `JSON` format, the extensive yet occasionally surprising in details `YAML` format, and the newest addition, `TOML`, which many people have not heard of yet. - -Your first task is to choose a format and then to document that choice. With this easy part out of the way, it is time to parse the configuration. - -It is sometimes a good idea to have a class that corresponds to the "abstract" data in the configuration. Because this code will do nothing with the configuration, this is the simplest way to show parsing logic. - -Imagine the configuration for a file processor: it includes an input directory, an output directory, and which files to pick up. - -The abstract definition for the configuration class might look something like: - - -``` -`from __future__ import annotations`[/code] [code] - -import attr - -@attr.frozen -class Configuration: -    @attr.frozen -    class Files: -        input_dir: str -        output_dir: str -    files: Files -    @attr.frozen -    class Parameters: -        patterns: List[str] -    parameters: Parameters -``` - -To make the format-specific code simpler, you will also write a function to parse this class out of dictionaries. Note that this assumes the configuration will use dashes, not underscores. This kind of discrepancy is not uncommon. - - -``` -def configuration_from_dict(details): -    files = Configuration.Files( -        input_dir=details["files"]["input-dir"], -        output_dir=details["files"]["output-dir"], -    ) -    parameters = Configuration.Paraneters( -        patterns=details["parameters"]["patterns"] -    ) -    return Configuration( -        files=files, -        parameters=parameters, -    ) -``` - -### JSON - -JSON (JavaScript Object Notation) is a JavaScript-like format. - -Here is an example configuration in JSON format: - - -``` -json_config = """ -{ -    "files": { -        "input-dir": "inputs", -        "output-dir": "outputs" -    }, -    "parameters": { -        "patterns": [ -            "*.txt", -            "*.md" -        ] -    } -} -""" -``` - -The parsing logic parses the JSON into Python's built-in data structures (dictionaries, lists, strings) using the `json` module and then creates the class from the dictionary: - - -``` -import json -def configuration_from_json(data): -    parsed = json.loads(data) -    return configuration_from_dict(parsed) -``` - -### INI - -The INI format, originally popular on Windows, became a de facto configuration standard. - -Here is the same configuration as an INI: - - -``` -ini_config=""" -[files] -input-dir = inputs -output-dir = outputs - -[parameters] -patterns = ['*.txt', '*.md'] -""" -``` - -Python can parse it using the built-in `configparser` module. The parser behaves as a `dict`-like object, so it can be passed directly to `configuration_from_dict`: - - -``` -import configparser - -def configuration_from_ini(data): -    parser = configparser.ConfigParser() -    parser.read_string(data) -    return configuration_from_dict(parser) -``` - -### YAML - -YAML (Yet Another Markup Language) is an extension of JSON that is designed to be easier to write by hand. It accomplishes this, in part, by having a long specification. - -Here is the same configuration in YAML: - - -``` -yaml_config = """ -files: -  input-dir: inputs -  output-dir: outputs -parameters: -  patterns: -  - '*.txt' -  - '*.md' -""" -``` - -For Python to parse this, you will need to install a third-party module. The most popular is `PyYAML` (`pip install pyyaml`). The YAML parser also returns built-in Python data types that can be passed to `configuration_from_dict`. However, the YAML parser expects a stream, so you need to convert the string into a stream. - - -``` -import io -import yaml -def configuration_from_yaml(data): -    fp = io.StringIO(data) -    parsed = yaml.safe_load(fp) -    return configuration_from_dict(parsed) -``` - -### TOML - -TOML (Tom's Own Markup Language) is designed to be a lightweight alternative to YAML. The specification is shorter, and it is already popular in some places (for example, Rust's package manager, Cargo, uses it for package configuration). - -Here is the same configuration as a TOML: - - -``` -toml_config = """ -[files] -input-dir = "inputs" -output-dir = "outputs" - -[parameters] -patterns = [ "*.txt", "*.md",] -""" -``` - -In order to parse TOML, you need to install a third-party package. The most popular one is called, simply, `toml`. Like YAML and JSON, it returns basic Python data types. - - -``` -import toml -def configuration_from_toml(data): -    parsed = toml.loads(data) -    return configuration_from_dict(parsed) -``` - -### Summary - -Choosing a configuration format is a subtle tradeoff. However, once you make the decision, Python can parse most of the popular formats using a handful of lines of code. - --------------------------------------------------------------------------------- - -via: https://opensource.com/article/21/6/parse-configuration-files-python - -作者：[Moshe Zadka][a] -选题：[lujun9972][b] -译者：[译者ID](https://github.com/译者ID) -校对：[校对者ID](https://github.com/校对者ID) - -本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 - -[a]: https://opensource.com/users/moshez -[b]: https://github.com/lujun9972 -[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/python_programming_question.png?itok=cOeJW-8r (Python programming language logo with question marks) diff --git a/translated/tech/20210625 Use Python to parse configuration files.md b/translated/tech/20210625 Use Python to parse configuration files.md new file mode 100644 index 0000000000..c6be0c7288 --- /dev/null +++ b/translated/tech/20210625 Use Python to parse configuration files.md @@ -0,0 +1,205 @@ +[#]: subject: "Use Python to parse configuration files" +[#]: via: "https://opensource.com/article/21/6/parse-configuration-files-python" +[#]: author: "Moshe Zadka https://opensource.com/users/moshez" +[#]: collector: "lujun9972" +[#]: translator: "zepoch" +[#]: reviewer: " " +[#]: publisher: " " +[#]: url: " " + +使用Python解析配置文件 +====== +第一步是选择配置文件的格式：INI、JSON、YAML 或 TOML。 + +![Python programming language logo with question marks][1] + +有时，程序需要足够的参数，将它们全部作为命令行参数或环境变量既不让人愉快也不可行。 在这些情况下，您将需要使用配置文件。 + +有几种流行的配置文件格式。 其中包括古老的（虽然偶尔定义不足）`INI`格式，虽然流行但有时难以手写的`JSON`格式，广泛但偶尔在细节方面令人惊讶的`YAML`格式，以及最新添加的`TOML `，很多人还没有听说过。 + +您的首要任务是选择一种格式，然后记录该选择。 解决了这个简单的部分之后就是时候解析配置了。 + +有时，在配置中拥有一个与“抽象“数据相对应的类是一个不错的想法。 因为这段代码不会对配置做任何事情，所以这是展示解析逻辑最简单的方式。 + +想象一下文件处理器的配置：它包括一个输入目录、一个输出目录和要提取的文件。 + +配置类的抽象定义可能类似于： + + +``` +`from __future__ import annotations`[/code] [code] + +import attr + +@attr.frozen +class Configuration: + @attr.frozen + class Files: + input_dir: str + output_dir: str + files: Files + @attr.frozen + class Parameters: + patterns: List[str] + parameters: Parameters +``` + +为了使特定于格式的代码更简单，您还将编写一个函数来从字典中解析此类。 请注意，这假设配置将使用破折号，而不是下划线。 这种差异并不少见。 + + +``` +def configuration_from_dict(details): + files = Configuration.Files( + input_dir=details["files"]["input-dir"], + output_dir=details["files"]["output-dir"], + ) + parameters = Configuration.Paraneters( + patterns=details["parameters"]["patterns"] + ) + return Configuration( + files=files, + parameters=parameters, + ) +``` + +### JSON + +JSON（JavaScript Object Notation）是一种类似于 JavaScript 的格式。 + +以下是 JSON 格式的示例配置： + + +``` +json_config = """ +{ + "files": { + "input-dir": "inputs", + "output-dir": "outputs" + }, + "parameters": { + "patterns": [ + "*.txt", + "*.md" + ] + } +} +""" +``` + +解析逻辑使用 `json` 模块将 JSON 解析为 Python 的内置数据结构（字典、列表、字符串），然后从字典中创建类： + + +``` +import json +def configuration_from_json(data): + parsed = json.loads(data) + return configuration_from_dict(parsed) +``` + +### INI + +INI 格式，最初只在 Windows 上流行，之后成为配置标准格式。 + +这是与 INI 相同的配置： + + +``` +ini_config=""" +[files] +input-dir = inputs +output-dir = outputs + +[parameters] +patterns = ['*.txt', '*.md'] +""" +``` + +Python 可以使用内置的 `configparser` 模块解析它。解析器充当类似 `dict` 的对象，因此可以直接传递给 `configuration_from_dict`： + + +``` +import configparser + +def configuration_from_ini(data): + parser = configparser.ConfigParser() + parser.read_string(data) + return configuration_from_dict(parser) +``` + +### YAML + +YAML (Yet Another Markup Language) 是 JSON 的扩展，旨在更易于手动编写。 部分 YAML 需要通过具有较长的规范来实现这一点。 + +以下是 YAML 中的相同配置： + + +``` +yaml_config = """ +files: + input-dir: inputs + output-dir: outputs +parameters: + patterns: + - '*.txt' + - '*.md' +""" +``` + +要让 Python 解析它，您需要安装第三方模块。 最受欢迎的是`PyYAML`（`pip install pyyaml`）。 YAML 解析器还返回可以传递给 `configuration_from_dict` 的内置 Python 数据类型。 但是，YAML 解析器需要一个字节流，因此您需要将字符串转换为字节流。 + + +``` +import io +import yaml +def configuration_from_yaml(data): + fp = io.StringIO(data) + parsed = yaml.safe_load(fp) + return configuration_from_dict(parsed) +``` + +### TOML + +TOML（Tom's Own Markup Language）旨在成为 YAML 的轻量级替代品。 规范比较短，已经在一些地方流行了（比如 Rust 的包管理器 Cargo 就用它来进行包配置）。 + +这是与 TOML 相同的配置： + + +``` +toml_config = """ +[files] +input-dir = "inputs" +output-dir = "outputs" + +[parameters] +patterns = [ "*.txt", "*.md",] +""" +``` + +为了解析 TOML，您需要安装第三方包。 最流行的一种被简单地称为 `toml`。 与 YAML 和 JSON 一样，它返回基本的 Python 数据类型。 + + +``` +import toml +def configuration_from_toml(data): + parsed = toml.loads(data) + return configuration_from_dict(parsed) +``` + +### Summary总结 + +选择配置格式是一种微妙的权衡。 但是，一旦您做出决定，Python 就可以使用少量代码来解析大多数流行的格式。 + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/21/6/parse-configuration-files-python + +作者：[Moshe Zadka][a] +选题：[lujun9972][b] +译者：[zepoch](https://github.com/zepoch) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/moshez +[b]: https://github.com/lujun9972 +[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/python_programming_question.png?itok=cOeJW-8r "Python programming language logo with question marks"