/**
 * 将一种类型转换为另一种类型,如果类型转换不允许，返回null
 * */
inline fun <reified T> Any.asType(): T? {
    return if (this is T) {
        this
  } else {
        null
  }
}



fun testAsType(charSequence: CharSequence?) {
    //书写不流畅，需要回到开始出增加()
  (charSequence as? String)?.length
  //一气呵成书写
  charSequence?.asType<String>()?.length
}