How-To-Write-Customized-Type.md

The document is about writing a customized verifiable type.

Using custom

walli provides custom method as follows:

import { custom } from 'walli'

const tenCheck = custom(function([reqA, reqB]) {
  // Passed
  if (reqA + reqB === 10) {
    return null
  }
  // Unlawful
  // Allows returning string, Unlawfulness, Reason or UnlawfulnessList
  return 'reqA + reqB should be equals 10.'
})

tenCheck.ok([1, 2]) === false
tenCheck.ok([8, 2]) === true

However, tenCheck is an instance of Verifiable rather than manageable Verifiable class.

so we should create the TenCheck Verifiable class

Creates the VerifiableClass

The two ways es5 and es6 are on the scene.

ES5

import { util } from 'walli'
const { createVerifiableClass } = util

const es5TenCheck = createVerifiableClass({
  _check(req) {
    return tenCheck.check(req)
  },
  getDisplayName() {
    return 'tenCheck'
  }
})

es5TenCheck().ok([1, 2]) === false

ES6

import { Verifiable, util } from 'walli'
const { funcify } from 'util'

class ES6TenCheck extends Verifiable {
  _check(req) {
    return tenCheck.check(req)
  },
  static displayName = 'tenCheck'
}
const es6TenCheck = funcify(ES6TenCheck)

es6TenCheck().ok([1, 2]) === false

Creates an standard TypeVerifiableClass

See Boolean.ts