Function initExtend

docs/themes/htx/source/js/vue.js:4547–4618

(Vue)

  /*  */

  function initExtend(Vue) {
    /**
     * Each instance constructor, including Vue, has a unique
     * cid. This enables us to create wrapped "child
     * constructors" for prototypal inheritance and cache them.
     */
    Vue.cid = 0;
    var cid = 1;

    /**
     * Class inheritance
     */
    Vue.extend = function(extendOptions) {
      extendOptions = extendOptions || {};
      var Super = this;
      var SuperId = Super.cid;
      var cachedCtors = extendOptions._Ctor || (extendOptions._Ctor = {});
      if (cachedCtors[SuperId]) {
        return cachedCtors[SuperId];
      }

      var name = extendOptions.name || Super.options.name;
      if ("development" !== "production" && name) {
        validateComponentName(name);
      }

      var Sub = function VueComponent(options) {
        this._init(options);
      };
      Sub.prototype = Object.create(Super.prototype);
      Sub.prototype.constructor = Sub;
      Sub.cid = cid++;
      Sub.options = mergeOptions(Super.options, extendOptions);
      Sub["super"] = Super;

      // For props and computed properties, we define the proxy getters on
      // the Vue instances at extension time, on the extended prototype. This
      // avoids Object.defineProperty calls for each instance created.
      if (Sub.options.props) {
        initProps$1(Sub);
      }
      if (Sub.options.computed) {
        initComputed$1(Sub);
      }

      // allow further extension/mixin/plugin usage
      Sub.extend = Super.extend;
      Sub.mixin = Super.mixin;
      Sub.use = Super.use;

      // create asset registers, so extended classes
      // can have their private assets too.
      ASSET_TYPES.forEach(function(type) {
        Sub[type] = Super[type];
      });
      // enable recursive self-lookup
      if (name) {
        Sub.options.components[name] = Sub;