Specifying adapter on 'adapter' property of DS.Store

I am having trouble specifying a custom adapter using the adapter property of the DS.Store as specified here, http://ift.tt/1TPWkv6.

Example 1:

app/store.js

import Ember from 'ember';
import DS from 'ember-data';

export default DS.Store.extend({

  adapter: 'custom',
});

app/adapters/custom.js

import Ember from 'ember';
import DS from 'ember-data';

export default DS.Adapter.extend({

  pathForType: function(type) {
    debugger; //Never goes in here
  },
});

Am I missing something here to get the Store to respect it's adapter property?

Additionally, would it be possible to have the adapter property be a computed property in order to dynamically choose an adapter to use?