ps杰夫！


Is it possible to inherit methods of a type without using embedded structs?

PropertyNodenode.GetStringPropertiesNodeProperties
package main

import "fmt"

type Properties map[string]interface{}

func (p Properties) GetString(key string) string {
    return p[key].(string)
}

type Nodes map[string]*Node

type Node struct {
    *Properties
}

func main() {
    allNodes := Nodes{"1": &Node{&Properties{"test": "foo"}}} // :'(
    singleNode := allNodes["1"]
    fmt.Println(singleNode.GetString("test"))
}

NodePropertiesProperty
package main

import "fmt"

type Properties map[string]interface{}

func (p Properties) GetString(key string) string {
    return p[key].(string)
}

type Nodes map[string]*Node

type Node Properties

func main() {
    allNodes := Nodes{"1": &Node{"test": "foo"}} // :)
    singleNode := allNodes["1"]
    fmt.Println(singleNode.GetString("test")) // :D
}

PropertiesNodeNodeNodeProperties
PropertiesNodeProperties
type Node PropertiesPropertiesNodeNodeProperties

It doesn't explain why this design choice was made but the Go Spec is at least specific if dry. If you read it exactly as it appears, with no interpretation, it is very accurate:

The method set of an interface type is its interface. The method set of any other type T consists of all methods declared with receiver type T

GetStringPropertiesNode

Further rules apply to structs containing anonymous fields, as described in the section on struct types.

...

A field or method f of an anonymous field in a struct x is called promoted if x.f is a legal selector that denotes that field or method f.

Promoted fields act like ordinary fields of a struct except that they cannot be used as field names in composite literals of the struct.

Given a struct type S and a type named T, promoted methods are included in the method set of the struct as follows:

  • If S contains an anonymous field T, the method sets of S and *S both include promoted methods with receiver T. The method set of *S also includes promoted methods with receiver *T.
  • If S contains an anonymous field *T, the method sets of S and *S both include promoted methods with receiver T or *T.
PropertiesNode

p.s. Hi Jeff!

这篇关于Golang嵌入式结构的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！