mixin.js

define(
  function() {
    function mixin() {
      var __config__ = {};
      this.setConfig = function(cfg) {
        __config__ = cfg;
      }
      
    } 
    return mixin;
  }
);

myComponent.js

define(
  [
    'component',
    'mixin'
  ], function(defineComponent) {
    function myComponent() {
      this.setConfig({});
    }
    return defineComponent(myComponent, mixin);
  } 
);