當結(jié)構(gòu)體的某個成員是map類型, 結(jié)構(gòu)體初始化后map需要單獨初始化，否則對map的操作會
“panic: assignment to entry in nil map”

import (
    "fmt"
)

//panic: assignment to entry in nil map
type Param map[string]interface{}

type Show struct {
    Param
}

func main() {
    s := new(Show)
    //s.Param["RMB"] = 10000 //panic: assignment to entry in nil map
    s.Param = map[string]interface{}{}
    s.Param = Param{}
    s.Param["RMB"] = 10000 
    fmt.Println(s)
}

當結(jié)構(gòu)體的某個成員是指向map類型的指針類型, ，對map的操作可能會發(fā)生如下兩種情況:
1: map未初始化,通過s.Param["RMB"]訪問，會導(dǎo)致"invalid operation: s.Param["RMB"] (type *Param does not support indexing)"
2: map未初始化, 通過s.Param["RMB"]訪問, 對該成員的訪問會導(dǎo)致"panic: runtime error: invalid memory address or nil pointer "
3: map已初始化，通過s.Param["RMB"]訪,會導(dǎo)致"invalid operation: s.Param["RMB"] (type *Param does not support indexing)", 所以對改指針的指向值的訪問需要解引用:

(*s.Param)["RMB"] 

package main
import "fmt"

type Param map[string]interface{}

type Show struct {
    *Param
}

func main() {
    s := new(Show)
    // s.Param["RMB"] = 10000 //invalid operation: s.Param["RMB"] (type *Param does not support indexing)
   // (*s.Param)["RMB"] = 10000 //panic: runtime error: invalid memory address or nil pointer dereference
    p := Param{}
    s.Param = &p
    //s.Param["RMB"] = 100000 //s.Param["RMB"] (type *Param does not support indexing)
    (*s.Param)["RMB"] = 100000
    fmt.Println(s.Param)   
}