that way, object users can t do things they are not supposed to do, access data they are not supposed to access, and generally be a pest 在这种方式下,对象用户无法做不准他们做的事,无法访问不准他们访问的数据,并且通常是有害数据。
is essentially a placeholder interface that specific command implementations implement for the purpose of allowing the command objects users to pass-in parameters that are specific to that command implementation 本质上是一个占位符接口,这个特定的command实现的目的是允许command对象的用户传入特定于这个command实现的参数。