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使我的readpackagefiles符合“parallel”函数

refactoring functional-programming asynchronous function javascript

Armeen Moon · 技术社区 · 7 年前

我得到了很多帮助 SO question 关于抓取目录和搜索文件。我在努力遵守我的 readPackageFiles 函数使用 Parallel 赋予我的功能;但是,我正在努力实现它。

错误:

UnhandledPromiseRejectionWarning: TypeError: Cannot use 'in' operator to search for 'throws' in 1
    at readFile (/Users/harwood/udev/dotcom-components/tools/dependency-version-comparison/node_modules/jsonfile/index.js:22:16)
    at Promise (/Users/harwood/udev/dotcom-components/tools/dependency-version-comparison/node_modules/universalify/index.js:13:12)
    at new Promise (<anonymous>)
    at readFile (/Users/harwood/udev/dotcom-components/tools/dependency-version-comparison/node_modules/universalify/index.js:7:14)
    at Array.map (<anonymous>)
    at /Users/harwood/udev/dotcom-components/tools/dependency-version-comparison/dist/index.js:1:1833
    at <anonymous>
(node:70097) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 63)
(node:70097) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
/Users/harwood/udev/dotcom-components/tools/dependency-version-comparison/node_modules/jsonfile/index.js:43
    callback(null, obj)

问题:我如何遵守 读取包文件 平行工作?

import {readdir, stat, readJson} from 'fs-extra';
import {join, basename} from 'path';

const Parallel = p =>
  ({
    map: async f =>
      Promise.all((await p).map(f))
    ,
    filter: async f =>
      Promise.all((await p).filter(f))
    ,
    flatMap: async f =>
      Promise.all((await p).map(f)).then(ys => [].concat(...ys))
    ,
  });
const files = async (path = '.') =>
  (await stat(path)).isDirectory()
  ? Parallel(readdir(path))
    .flatMap(f => files(join(path, f)))
  : [path];

const search = async (query, path = ".") =>
  Parallel (files (path))
    .filter (f => basename (f) === query);

// How can I write this to use Parallel    
const readPackageFiles = async (packages) => await Promise.all(packages.map(async x => (await readJson(x))));

// this will not work but it's my attempt

const readPackageFilesNOTWORKING = async(path = ".") =>
  Parallel (search('package.json', path))
    .map (readJson)

用途:

search('package.json', '.')
  .then(readPackageFiles)
  .then(console.log);

0 回复 | 直到 7 年前

Mulan 7 年前

我希望你能仔细看一下相关的问答。我怀疑你需要这样的功能, readPackages ,在 first link 我和你分享了-

const { readFile } =
  require ("fs") .promises

const readPackages = async (path = ".") =>
  Parallel (search ("package.json", path))
    .map (readFile)
    .then
      ( buffers =>
          buffers .map (b => JSON .parse (String (b)))
      )

readPackages (".") .then (console.log, console.error)
// [ ... ]

注: fs-extra 我的任何答案都不需要。