go - 为什么kubernetes内部使用字符串指针而不是字符串？

Question

不仅是字符串指针，还有bool指针、int指针等

参见: https://github.com/kubernetes/cli-runtime/blob/5c4694c3aa38d6f710b2e3b18598f9d83f1aae3b/pkg/genericclioptions/config_flags.go#L322-L336

golang 似乎无法从 Constant Pool 之类的东西中获益。

语言

package main

import (
    "fmt"
)

func StringPtr(s string) *string {
    return &s
}

func main() {
    fmt.Println(StringPtr("")) // outputs "0x40e128"
    fmt.Println(StringPtr("")) // outputs "0x40e138"
}

python

id("") // outputs "4459080368"
id("") // outputs "4459080368"

Answer 1

我的猜测是这样做是为了确保配置标志的值在更改时随处更新。

这个例子可能会有帮助

package main

import "fmt"

func stringPointer(s string) *string {
    return &s
}

type Config struct {
    String  string
    Pointer *string
}

func NewConfig() Config {
    return Config{
        String:  "default",
        Pointer: stringPointer("default"),
    }
}

var (
    config = NewConfig()

    String  = config.String
    Pointer = config.Pointer
)

func PrintVars() {
    fmt.Printf("config.String: %v\n", config.String)
    fmt.Printf("config.Pointer: %v\n", *config.Pointer)
    fmt.Printf("String: %v\n", String)
    fmt.Printf("Pointer: %v\n", *Pointer)
    fmt.Println("-------------------------")
}

func main() {
    PrintVars()
    config.String = "new value"
    *config.Pointer = "new value"
    PrintVars()
    String = "even newer value"
    *Pointer = "even newer value"
    PrintVars()
}

输出:

config.String: default
config.Pointer: default
String: default
Pointer: default
-------------------------
config.String: new value
config.Pointer: new value
String: default
Pointer: new value
-------------------------
config.String: new value
config.Pointer: even newer value
String: even newer value
Pointer: even newer value
-------------------------