Package Exports

farrow-module

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Readme

farrow-module

A module abstraction providing dependencies management

Installation

# from npm
npm install --save farrow-module

# from yarn
yarn add farrow-module

Glossary

Module:
- Any Class which extends Module
- it's a basic unit for writing logic code
- it should not define custom constructor parameters
- it should not be instantiated via the new keyword manually
- everything it needed is via this.use(DepClass)
Provider
- it can be created via createProvider<Type>(defaultValue)
- it should be attached to Container via Provider.provide(value)
- it should be placed only once for a Container, duplicated is not allow
Container
- Any Class which extends Container
- it's the entry of our code of modules
- it should be instantiated by the new keyword
- it can use [ModuleProviderSymbol] field for injecting the value created by Provider

Usage

import { Module, Container, createProvider, ModuleProviderSymbol } from 'farrow-module'

type PageInfo = {
  url: string
  env: string
}

/**
 * create a provider carries extra data
 */
const PageInfo = createProvider<PageInfo>()

/**
 * define a module class and inject deps via this.use(Dep)
 */
class User extends Module {
  // inject PageInfo
  page = this.use(PageInfo)
  path = `${this.page.url}/user`
  // supporting circular dependencies via getter
  get product() {
    return this.use(Product)
  }
}

/**
 * define a module class and inject deps via this.use(Dep)
 */
class Product extends Module {
  // inject PageInfo
  page = this.use(PageInfo)
  path = `${this.page.url}/product`
  // supporting circular dependencies via getter
  get user() {
    return this.use(User)
  }
}

/**
 * define a module class and inject deps via this.use(Dep)
 */
class Root extends Module {
  // inject PageInfo
  page = this.use(PageInfo)
  // inject User
  user = this.use(User)
  // inject Product
  product = this.use(Product)

  // self-injection via getter
  get self() {
    return this.use(Root)
  }

  getInfo() {
    return {
      url: this.page.url,
      env: this.page.env,
      user: this.user.path,
      product: this.product.path,
    }
  }
}

// prepared value of provider
const pageInfoForApp = PageInfoProvider.provide({
  url: '/path/for/app',
  env: 'app',
})

// prepared value of provider
const pageInfoForNew = PageInfoProvider.provide({
  url: '/path/for/new',
  env: 'new',
})

/**
 * define a module-container class for entry
 * use [ModuleProviderSymbol] filed for providing Provider
 */
class App extends Container {
  [ModuleProviderSymbol] = [pageInfoForApp]

  // app.root is equal to app.root1
  root = this.use(Root)

  root1 = this.use(Root)

  /**
   * create a new Root and provide new Provider
   *  app.root2 is not equal to app.root, it's a new one
   */
  root2 = this.new(Root, {
    providers: [pageInfoForNew],
  })
}

const app = new App()

app.root.getInfo()

API

Module#use(DepClass)

module.use(DepClass) will read or create a DepClass instance from the Container

Module#new(DepClass, options?)

module.new(DepClass, options) will create a new DepClass instance

options.providers, an list of value created by Provider for injecting.

Container#[ModuleProviderSymbol]

ModuleContainer#[ModuleProviderSymbol] is a place for injecting the value of any Provider in Container

Container.from(Class)

Container.from(Class) can extends a existed Class make it become a Container which supports this.use() and this.new()

createProvider(defaultValue?)

createProvider<Type>(defaultValue?) create a Provider by given Type and defaultValue

Provider.provide(value): create a injectable value of Provider for Container
Provider.defaultValue: the defaultValue of Provider, it's optional, maybe undefined