const值在匿名struct字段中做什么？

Question

Given the following code:

type NodeType int

const (
    NodeText NodeType = iota
    NodeAction
    // etc..
)

type ListNode struct {
    NodeType
}

What is the explanation of including the NodeType type as an anonymous field in the ListNode struct? Does it serve as some sort of identifier for the struct?

Answer 1

For such an anonymous or embedded field, per The Go Programming Language Specification,

The unqualified type name acts as the field name.

In your case, you can write the following:

var node1 ListNode
node1.NodeType = NodeText

or

node2 := ListNode{NodeText}

or

node3 := ListNode{
    NodeType: NodeText,
}

All three create the same value.