如何比较地图的身份或本例中发生了什么？

我正在尝试比较两张地图的身份

package main

import "fmt"

func main() {
    a := map[int]map[int]int{1:{2:2}}

    b := a[1]
    c := a[1]

    // I can't do this: 
    // if b == c
    // because I get: 
    // invalid operation: b == c (map can only be compared to nil)

    // but as far as I can tell, mutation works, meaning that the 2 maps might actually be identical
    b[3] = 3

    fmt.Println(c[3]) // so mutation works...


    fmt.Printf("b as pointer::%p\n", b)
    fmt.Printf("c as pointer::%p\n", c) 

    // ok, so maybe these are the pointers to the variables b and c... but still, those variables contain the references to the same map, so it's understandable that these are different, but then I can't compare b==c like this
    fmt.Printf("&b::%p\n", &b)
    fmt.Printf("&c::%p\n", &c)  

    fmt.Println(&b == &c)
}

这会产生以下输出：

3
b as pointer::0x442280
c as pointer::0x442280
&b::0x40e130
&c::0x40e138
false

让我特别困惑的是，虽然b as pointer::0x442280 and c as pointer::0x442280似乎具有相同的值，这确实证实了我的怀疑，即这些变量以某种方式指向同一个字典。

那么有谁知道我怎样才能做到这一点b and c是“同一个对象”吗？

不漂亮，但你可以使用reflect.ValueOf(b).Pointer():

package main

import (
    "fmt"
    "reflect"
)

func main() {
    a := map[int]map[int]int{1: {2: 2}}

    b := a[1]
    c := a[1]

    d := map[int]int{2: 2}

    fmt.Println(reflect.ValueOf(b).Pointer() == reflect.ValueOf(c).Pointer())
    fmt.Println(reflect.ValueOf(c).Pointer() == reflect.ValueOf(d).Pointer())
}