events.js

var _ = require('../util')

module.exports = {

  acceptStatement: true,

  bind: function () {
    var child = this.el.__vue__
    if (!child || this.vm !== child.$parent) {
      _.warn(
        '`v-events` should only be used on a child component ' +
        'from the parent template.'
      )
      return
    }
  },

  update: function (handler, oldHandler) {
    if (typeof handler !== 'function') {
      _.warn(
        'Directive "v-events:' + this.expression + '" ' +
        'expects a function value.'
      )
      return
    }
    var child = this.el.__vue__
    if (oldHandler) {
      child.$off(this.arg, oldHandler)
    }
    child.$on(this.arg, handler)
  }

  // when child is destroyed, all events are turned off,
  // so no need for unbind here.

}