英文:
Or inside condition
问题
我有这段代码：
if ev, ok := evt.(*ATypeEvent); ok {//处理 ATypeEvent} else if ev, ok := evt.(*BTypeEvent); ok {//处理 BTypeEvent} else if ev, ok := evt.(*CTypeEvent); ok {//处理 CTypeEvent}
现在我有另外三种事件类型，它们都可以归类到其他三种类型之一，我认为我需要一个或运算。
但是经过多次尝试，我还没有找到正确的方法。下面的代码是不起作用的：
if ev, ok := evt.(*ATypeEvent) || evt.(*XTypeEvent); ok {//处理 ATypeEvent 和 X} else if ev, ok := evt.(*BTypeEvent) || evt.(*YTypeEvent); ok {//处理 BTypeEvent 和 Y} else if ev, ok := evt.(*CTypeEvent) || evt.(*ZTypeEvent); ok {//处理 CTypeEvent 和 Z}
也不是这样写：
if ev, ok := evt.(*ATypeEvent) || ev, ok := evt.(*XTypeEvent); ok {
或者这样写：
if ev, ok := (evt.(*ATypeEvent) || evt.(*XTypeEvent ) ); ok {
如何正确实现这个功能呢？
英文:
I have this code:
if ev, ok := evt.(*ATypeEvent); ok {//process ATypeEvent} else if ev, ok := evt.(*BTypeEvent); ok {//process BTypeEvent} else if ev, ok := evt.(*CTypeEvent); ok {//process CTypeEvent}
It so now happens that I have 3 more event types, which all fit into one of the other 3 - I'd think I need a an OR.
But after several tries, I haven't been able to figure how to do it.
This doesn't work:
if ev, ok := evt.(*ATypeEvent) || evt.(*XTypeEvent); ok {//process ATypeEvent and X} else if ev, ok := evt.(*BTypeEvent) || evt.(*YTypeEvent); ok {//process BTypeEvent and Y} else if ev, ok := evt.(*CTypeEvent) || evt.(*ZTypeEvent); ok {//process CTypeEvent and Z}
nor something like
if ev, ok := evt.(*ATypeEvent) || ev, ok := evt.(*XTypeEvent); ok {
nor
if ev, ok := (evt.(*ATypeEvent) || evt.(*XTypeEvent ) ); ok {
How can this be done correctly?
答案1
得分: 1
请稍等，我会为您进行翻译。
英文:
Use a type switch as explained in Effective Go, a highly recommended resource for you to read and understand many things in Go:
switch v := ev.(type) {case *ATypeEvent, *XTypeEvent:// process ATypeEvent and Xcase *BTypeEvent, *YTypeEvent:// process BTypeEvent and Ycase *CTypeEvent, *ZTypeEvent:// process CTypeEvent and Zdefault:// should never happenlog.Fatalf("error: unexpected type %T", v)}
As for why your approach didn't work, Go's || and && operators require values of type bool and result in a single value of type bool, so assigning to ev, ok won't work as you wanted, nor will using a type assertion as a Boolean value. Without a type switch, you're stuck doing something like this:
if ev, ok := evt.(*ATypeEvent); ok {//process ATypeEvent} else if ev, ok := evt.(*XTypeEvent); ok {//process XTypeEvent} else if ...
答案2
得分: 1
另一种选择是在接口上定义一个处理 evt 的方法。
func (a *ATypeEvent) Process(...) ... {//处理 ATypeEvent}func (x *XTypeEvent) Process(...) ... {//处理 XTypeEvent}func (b *BTypeEvent) Process(...) ... {//处理 BTypeEvent}以此类推。
英文:
Another option is to define a method on the interface for evt.
func (a *ATypeEvent) Process(...) ... {//process ATypeEvent}func (x *XTypeEvent) Process(...) ... {//process XTypeEvent}func (b *BTypeEvent) Process(...) ... {//process BTypeEvent}
and so on.
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。
评论