Create a non-singleton class from a singleton - yargs

README.md

A singleton makes sense when it prevent multiple access to a resource than must not be accessed in that way. But sometimes a singleton design is used because it is sufficient for expected usage. But that may block expanded usage unecessarily.

ES6 dynamic import can import a singelton module into a closure allowing a singleton to become a non-singleton class. See the file yargs-class.mjs below.

The result of test-yargs0class.mjs -

argv[0]= {
  "_": [
    "goo"
  ],
  "car": "CAR",
  "r": "CAR",
  "caz": "CAZ",
  "z": "CAZ",
  "$0": "src/test-yargs-obj.mjs"
}
argv[1]= {
  "_": [
    "goo"
  ],
  "car": "BAR",
  "r": "BAR",
  "caz": "BAZ",
  "z": "BAZ",
  "$0": "src/test-yargs-obj.mjs"
}

test-yargs-class.mjs

'use strict'

import createYargsClass from './yargs-class.mjs'

(async function () {
    let myArgv = [
        ["goo", "--car", "CAR", "--caz", "CAZ"],
        ["goo", "--car", "BAR", "--caz", "BAZ"]
    ]
    var yac = []
    yac[0] = await createYargsClass(myArgv[0], process.cwd())
    yac[1] = await createYargsClass(myArgv[1], process.cwd())

    var argv=[]
    for (let i = 0; i < 2; i++) {
        argv[i] = yac[i].yargs.command("goo", "GOO", {
            car: {
                description: ' car arg ',
                alias: 'r',
                type: 'string'
            },
            caz: {
                description: ' caz arg ',
                alias: 'z',
                type: 'string'
            },
        })
            .argv
    }
    console.log("argv[0]=", JSON.stringify(argv[0],0,2))
    console.log("argv[1]=", JSON.stringify(argv[1],0,2))
})()

yargs-class.mjs

'use strict'
class YargsClass {
    constructor(yargs){
        this.yargs=yargs
    }
}

export default async function createYargsClass(targetArgv, cwd){
    var yargsModule = await import('../node_modules/yargs/yargs.js')
    var yargs = yargsModule.default(targetArgv, cwd)
    return new YargsClass(yargs)
}