Method mixin

packages/blockly/core/block.ts:1916–1937

* Add key/values from mixinObj to this block object. By default, this method * will check that the keys in mixinObj will not overwrite existing values in * the block, including prototype values. This provides some insurance against * mixin / extension incompatibilities with future block fea

(mixinObj: AnyDuringMigration, opt_disableCheck?: boolean)

   * @param opt_disableCheck Option flag to disable overwrite checks.
   */
  mixin(mixinObj: AnyDuringMigration, opt_disableCheck?: boolean) {
    if (
      opt_disableCheck !== undefined &&
      typeof opt_disableCheck !== 'boolean'
    ) {
      throw Error('opt_disableCheck must be a boolean if provided');
    }
    if (!opt_disableCheck) {
      const overwrites = [];
      for (const key in mixinObj) {
        if ((this as AnyDuringMigration)[key] !== undefined) {
          overwrites.push(key);
        }
      }
      if (overwrites.length) {
        throw Error(
          'Mixin will overwrite block members: ' + JSON.stringify(overwrites),
        );
      }
    }
    Object.assign(this, mixinObj);
  }

  /**
   * Interpolate a message description onto the block.