实现“通用”节点列表

Question

I'd like to implement a linked list with nodes. Each node can be of a different type (Foo, Bar and Baz - will be 40-50 different nodes) and each type has common fields (prev, next, ...) and some node-specific fields.

I have a hard time to come up with a solution that looks reasonable. Now the question: what approach can I take to make this more elegant?

Here is my (dummy) main.go:

package main

import (
    "fmt"

    "node"
)

func main() {
    a := node.NewFoo()
    fmt.Println(a)

    b := node.NewBar()
    fmt.Println(b)

    node.Append(a, b)
}

and here is my implementation (node.go):

package node

type Node interface {
}

type FooNode struct {
    prev               Node
    next               Node
    FieldSpecificToFoo int
}

type BarNode struct {
    prev               Node
    next               Node
    FieldSpecificToBar int
}

type BazNode struct {
    prev               Node
    next               Node
    FieldSpecificToBaz int
}

func NewFoo() *FooNode {
    return &FooNode{}
}

func NewBar() *BarNode {
    return &BarNode{}
}

func NewBaz() *BazNode {
    return &BazNode{}
}

func Append(a, b Node) {
    // set next and prev pointer
    switch v := a.(type) {
    case FooNode:
        v.next = b
    case BarNode:
        v.next = b
    case BazNode:
        v.next = b
    }

    switch v := b.(type) {
    case FooNode:
        v.prev = a
    case BarNode:
        v.prev = a
    case BazNode:
        v.prev = a
    }
}

This is obviously a pretty crappy implementation. What can I do in this case?

Answer 1

I am not entirely sure I understand what you are trying to do but here are a few ideas:

• Use the standard container

• Make the node contain your "user" data as an interface:

  type Node struct {
      next *Node
      Value interface{}
  }
  

This is (somewhat) like doing it in C with a void* to user data.