指针，数组和切片的结构值 [英] Struct value of pointer, array and slice

问题描述

我想有一个通用的方法，无论它是作为指针，切片还是数组提供，都将始终返回结构值.

I want to have a generic way which will always return the struct value no matter if it is provided as pointer, slice or array.

我的处理方法是:

func main() {
    p := Person{}

    if value(p).Kind() != reflect.Struct {
        fmt.Printf("Error 1")
    }
    if value(&p).Kind() != reflect.Struct {
        fmt.Printf("Error 2")
    }   
    if value([]Person{p}).Kind() != reflect.Struct {
        fmt.Printf("Error 3")
    }
    if value(&[]Person{p}).Kind() != reflect.Struct {
        fmt.Printf("Error 4")
    }
}

func value(m interface{}) reflect.Value {
    v := reflect.ValueOf(m)

    switch v.Kind() {
    case reflect.Ptr:
        v = v.Elem()

        fallthrough
    case reflect.Slice, reflect.Array:
        v = v.Elem()
    }

    return v
}

去游乐场

如您所见，问题在于将结构从 slice 或 array 移出.

As you can see the problem lays with in getting the struct out of a slice or array.

如何扩展上述函数以从数组或切片中获取struct值?

更新:我要做的是将 [] People 变成 People .

Update: What I want to do is turn []People into People.

推荐答案

如果即使分片为nil，也只想要类型，则可以使用

If you just want the type even if the slice is nil, you can use something like this:

func value(m interface{}) reflect.Type {
    t := reflect.Indirect(reflect.ValueOf(m)).Type()
    if t.Kind() == reflect.Slice || t.Kind() == reflect.Array {
        t = t.Elem()
        if t.Kind() == reflect.Ptr {
            t = t.Elem()
        }
        return t

    }
    return t
}

关于 Type.Elem()，来自 http://golang.org/pkg/reflect/#Type :

//Elem返回类型的元素类型.

// Elem returns a type's element type.

//如果类型的种类不是Array，Chan，Map，Ptr或Slice，它会惊慌.

// It panics if the type's Kind is not Array, Chan, Map, Ptr, or Slice.

//编辑对功能进行了更新，使其也适用于切片指针.

//edit updated the function to work on a slice of pointers as well.

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