topic Re: Can Accessor not be used as Singleton? in ArcGIS JavaScript Maps SDK Questions

Can Accessor not be used as Singleton?

BenFousek — Sat, 11 Dec 2021 20:54:13 GMT

I'm playing around with Accessor and trying to return a Singleton but requiring the module anytime after first require on booting the app just returns an Object.

// returns Singleton
define([
  'dojo/_base/declare',
  'dojo/Stateful',
  'dojo/Evented'
], function (
  declare,
  Stateful,
  Evented
) {
  var _instance = null;

  var Model = declare([Stateful, Evented], {
  // stuff
  });

  if (!_instance) {
    _instance = new Model();
  }
  return _instance;
});

// returns Object
define([
  'esri/core/Accessor',
  'dojo/Evented'
], function (
  Accessor,
  Evented
) {
  var _instance = null;

  var Model = Accessor.createSubclass([Evented], {
  // stuff
  });

  if (!_instance) {
    _instance = new Model();
  }
  return _instance;
});‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Can Accessor not be used as Singleton?

deleted-user-iPdcWUgWcsoy — Sat, 11 Dec 2021 20:54:15 GMT

Perhaps you find further informations in this link for real singletons (entry by "JonS"). We use it in our applications.

http://stackoverflow.com/questions/4334437/dojo-singleton-or-at-least-static-method-variable

Your second sample code can look like this.

// returns Object
define([
  'esri/core/Accessor',
  './Singleton',
  'dojo/Evented'
], function (
  Accessor,
  Evented
) {
  var Model = Singleton(Accessor.createSubclass([Evented], {
  // stuff
  }));

  return Model.getInstance(); // or just return the singleton
});‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Can Accessor not be used as Singleton?

BenFousek — Fri, 26 May 2017 16:07:05 GMT

Thanks for the reply Martin. That's more elegant.

My problem was configuring dojo and booting the app in the same require(). Dojo didn't like the relative path when requiring the model after boot.

Moved dojo config to its own require to fix problem.