initialise

Lazy initialization / require wrapper. Makes sure you only load the modules once when you need them.

npm install initialise
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initialise

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initialise is a small module that allows you to lazy require/initialise modules when they are accessed. This allows you to easily build light weight core modules that can be shared with various of parts of your infrastructure / services.

Installation

npm install initialise --save

Example

The following example illustrates the power and usage of initialise.

//
// Require the module and hook it on to the exports object
//
var initialise = require('initialise').on(exports);

//
// You can now define lazy loaded modules:
//
initialise('foo', function foo() {
  return require('./foo');
});

We now have a exports.foo method. When you access it, it will load the module foo once and store the result of it. But this is just a simple example of it's use. You can could also use it to require pre-configured database connections, loggers, configuration files and what more. It comes with a small register function that you can use to register a destruction handler. This ensures that every initialised module is cleaned up correctly when initialise.end is called.

var initialise = require('initialise').on(exports);

initialise('config', function () {
  return require('./configuration.json');
});

initialise('redis', function redisClient(register) {
  var config = this.config.get('redis')
    , auth = config.auth || config.password || config.pass
    , redis = require('redis').createClient(config.port, config.host)
    , self = this;

  if (auth) redis.auth(auth);

  redis.on('error', function error(err) {
    console.error(err);
  });

  //
  // Add a clean-up hook. The `redis.quit()` method will wait until all replies
  // have been read instead of forcefully close the connection.
  //
  register('redis', 'quit');

  return redis;
});
initialise.end();

In the example above you also see this.config, this is actually a reference to the exports.config and will lazy load the ./configuration.json file that contains our example redis configuration. It passes the string quit to the register method as that's the method for redis to savely nuke the connection.

If you want to do more advanced clean up operations or need to clean up something that is not method on the returned object you can pass it a function as well:

register('redis', function () {
  // This function will be called when initialise.end() is called.
});

The destruction can also be done async, but initialise is pretty dumb so you have to help it a bit so it understands that this clean up operation is async. So in the case of redis it would simply become:

``` initialise('redis', function create(register) { .. do your redis creation magic, same as example above ..

register.async('redis', 'quit');

// // As you can see above, we call register.async instead of just register so // we can pass in a callback to the method and wait for it to be called. // });

License

MIT

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