无法使接口切片正常工作

Question

What I'm trying to do is to create a slice of an interface type and populating it with some struct types that are implementing this interface.

chans := []chan Event {
    make(chan FileEvent),
    make(chan NetworkEvent),
}

But this fails with cannot use make(chan FileEvent) (type chan FileEvent) as type chan Event in array or slice literal.

Now I am aware that this is meant to be that way.
However the suggested solution is a) not practical because I have a bunch of different types and cannot easily iterate over them and b) I cannot even get it to work, it still gives me the same error. I tried:

chans := make([]chan Event, 2)
chans[0] = make(chan FileEvent)

Do you guys know what I'm doing wrong or how this can be solved elegantly? Thanks a lot !!

Here are the definitions of the types:

type Event interface {
  GetId() string
}

type FileEvent struct {
}

func (e FileEvent) GetId() string {
  return "FileEvent"
}

Answer 1

Event may be an interface type, but chan Event is not; it is a specific channel type. A []chan Event is a slice, in which every element must be of type chan Event. However, a chan Event could accept messages of any type implementing Event.

Why? Consider this code:

chans := []chan Event {
    make(chan FileEvent),
    make(chan NetworkEvent),
}

ch := chans[0] // ch is of type chan Event because that's the type of elements of chans
ch <- NetworkEvent{} // Uh oh - we just tried to send a NetworkEvent to what's actually a chan FileEvent!

The send would be compile-time legal if your code were legal, but would cause a runtime type error, which is not allowed in Go as it uses strict static typing.

You could, however, make them all chan Event, and then you could send whatever types you needed, and use type assertions when receiving from those channels.