Woodpecker NPM

woodpecker

A lightweight dependency injection framework

Installation

npm install woodpecker --save

Usage

Register a service

var woodpecker = require('woodpecker');

// Simple logger service function
function Logger() {
  this.log = function(msg) {
    console.log(msg);
  }
}

// The service will be registered under the name 'logger'. Works only with named function
woodpecker.service(Logger);

// Use custom names
woodpecker.service('myService', Logger);

Request a service

// Request service
var serviceInstance = woodpecker.service('logger');

// Now the service can be used
serviceInstance.log('Hello World');

Using the dependency injection

// Create some functions
function Logger() {
  this.log = function(msg) {
    console.log(msg);
  }
}

function UserDAO() {
  this.getUser = function(id) {
    return {
      id: id,
      name: 'Theo',
      age: 28
    }
  }
}

// The required service instances will be automatically injected, if the parameter names match the registered services
function UserService(logger, userDAO) {
  this.print = function() {
    logger.log(userDAO.getUser().name);
  }
}

// Register the services
woodpecker.service(Logger);
woodpecker.service(UserDAO);
woodpecker.service(UserService);

// Load the service. Required services (logger and userDAO) will be injected
var userService = woodpecker.service('userService');

// Use the service
userService.print();

Using proxy services

Proxy service always holds the current registered service. To get an proxy instance surround the service name with '$' (e.g. $logger$ for a service named 'service').

// Register a service which use a service named looger
function ServiceWithProxy($logger$) {
  this.hello = function() {
    return $logger$.log('Hello');
  }
}

// Register a service named logger
woodpecker.service('logger', function() {
  this.log = function(msg) {
    console.log(msg.toLowerCase());
  }
});

// Use the service
var serviceWithProxy = woodpecker.service('serviceWithProxy');
serviceWithProxy.hello() // prints 'hello' on console

// Register a new service named logger
woodpecker.service('logger', function() {
  this.log = function(msg) {
    console.log(msg.toUpperCase());
  }
});

serviceWithProxy.hello() // prints 'HELLO' on console