How to implement a linked list

I'm trying to implement a sorted linked list in Go. And I'm having a hard time coming up with a generic way to make the linked list work with any type that can by compared with itself. Since its a sorted list, I want the 'go compiler' to ensure that the values being inserted into the linked list can be compared.

For example,

import "linkedlist"

type Person struct {
  name string
}

func main() {
  l := linkedlist.New()
  p := Person{"Jay"}
  l.insert(p)
}

In the above example, how do I make the compiler ensure that the value 'p' which has type 'Person' can be compared with another value which also has type 'Person'. I want the compiler to catch the error in those situations where the value being inserted is not an appropriate value.

I can do something like this,

import "linkedlist"

type Element interface {
  func IsGreater(v Element{}) bool
}

type Person struct {
  name string
  age int
}

func (p *Person) IsGreater(p1 interface{}) bool {
  if ok, v := p1.(Person); ok && p.age > v.age {
    return true
  }
  return false
}

And then, within the "insert" function of the linked list I can use the IsGreater function to decide where to place the Element in the linked list.

My question is...

1. Is there a better way to do this? Something that is a lot better than the solution above.

I've already gone through sort.Sort and seen how its done in that package. The way its done there is to create a new type for a slice of the type and then make that new type fulfill the sort interface by implementing Len, Less and Swap.

I can probably do the same thing here in my case as well. But having to create a new slice type and then implement a few functions to satisfy an interface, when I'll only be dealing with 2 values of the same type at a time.. seems a bit overkill to me.

Because Golang do not support generics, So all of containers should use interface{} and type assert, I think no better solution for your requirement.

Library functions for this already exist:

http://golang.org/pkg/container/list/

http://golang.org/pkg/container/ring/

You can compare the lists with reflect.DeepEqual.

If you want to implement a linked list that uses type checking, make an embedded struct for the list type MyLinkedList struct { *list.List} and one for the items in the list type Element struct{ *List.Element }. You can then implement all the methods of list.List and over-ride as necessary with your type checks.