Question

我有一个带有切片字段的.cc-selector{ position: relative; left: 600px; top: 250; } .cc-selector input{ margin:0;padding:0; -webkit-appearance:none; -moz-appearance:none; appearance:none; } .visa{background-image:url(http://i.imgur.com/lXzJ1eB.png);} .mastercard{background-image:url(http://i.imgur.com/SJbRQF7.png);} .cc-selector input:active +.drinkcard-cc{opacity: .9;} .cc-selector input:checked +.drinkcard-cc{ -webkit-filter: none; -moz-filter: none; filter: none; } .drinkcard-cc{ cursor:pointer; background-size:contain; background-repeat:no-repeat; display:inline-block; width:100px;height:70px; -webkit-transition: all 100ms ease-in; -moz-transition: all 100ms ease-in; transition: all 100ms ease-in; -webkit-filter: brightness(1.8) grayscale(1) opacity(.7); -moz-filter: brightness(1.8) grayscale(1) opacity(.7); filter: brightness(1.8) grayscale(1) opacity(.7); } .drinkcard-cc:hover{ -webkit-filter: brightness(1.2) grayscale(.5) opacity(.9); -moz-filter: brightness(1.2) grayscale(.5) opacity(.9); filter: brightness(1.2) grayscale(.5) opacity(.9); }结构：

Favorites

我有type Favorites struct { Color string Lunch string Place string Hobbies []string }，其中包含其他结构：

Person

我想看看是否在Person上设置了type Person struct { Name string Favorites Favorites }字段。对于其他类型的字段，例如字符串或int，我会将该字段与零值（分别为“”或0）进行比较。

如果我尝试与下面的零进行比较，我会收到错误Favorites：

invalid operation: p2.Favorites == zeroValue (struct containing []string cannot be compared)

这符合规范（https://golang.org/ref/spec#Comparison_operators）中定义的内容。

除了繁琐地比较每个字段（并且如果结构发生变化时必须记住更新它）之外，还有其他方法可以进行这种比较吗？

一个选项是使“收藏夹”字段成为指向结构而不是结构本身的指针，然后只与nil进行比较，但这是在一个大型代码库中，所以我宁愿不在这种情况下做出可能影响深远的更改

https://play.golang.org/p/d0NSp8eBes

Answer 1

According to this，您可以使用reflect.DeepEqual()，但可能应该自己编写：

type Favorites struct {
    Color string
    Lunch string
    Place string
    Hobbies []string 
}

func (favs *Favorites) Equals(other *Favorites) bool {
    color_eq := favs.Color == other.Color
    lunch_eq := favs.Lunch == other.Lunch
    place_eq := favs.Place == other.Place
    hobbies_eq := len(favs.Hobbies) == len(other.Hobbies)
    if hobbies_eq {  // copy slices so sorting won't affect original structs
        f_hobbies := make([]string, len(favs.Hobbies))
        o_hobbies := make([]string, len(other.Hobbies))
        copy(favs.Hobbies, f_hobbies)
        copy(other.Hobbies, o_hobbies)
        sort.Strings(f_hobbies)
        sort.Strings(o_hobbies)
        for index, item := range f_hobbies {
            if item != o_hobbies[index] {
                hobbies_eq = false
            }
        }
    }
    return (color_eq && lunch_eq && place_eq && hobbies_eq)
}

然后用：

调用它

p2.Favorites.Equals(zeroValue)

有没有办法将结构与切片字段与零值结构进行比较？

1 个答案: