怎么使用slot重写抽象节点呀？大佬们指点一下，下面是代码

 <item 
                    wx:for="{{pitem}}" 
                    wx:key="id"
                    wx:for-item="sitem" 
                    wx:for-index="sidx" 
                    item="{{sitem}}" 
                    pidx="{{pidx}}" 
                    sidx="{{sidx}}"
                    cdata="{{cdata}}"
                    bind:listener="_onListener"/>