英文:
Go access pointer value if its passed as interface{}
问题
我正在编写一个程序，需要访问作为interface{}传递的指针的值。
以下是示例代码：
package main
import (
"reflect"
)
type Test struct {
Names []string
}
func main() {
arr := []string{"a", "a", "a", "a", "a", "a"}
obj := new(Test)
obj.Names = arr
TestFunc(obj)
}
func TestFunc(obj interface{}) {
rt := reflect.TypeOf(obj)
switch rt.Kind() {
case reflect.Struct:
return
case reflect.Ptr:
TestFunc(reflect.ValueOf(obj).Elem().Interface())
}
}
问题是，当我将指针传递给TestFunc()时，我不知道如何在函数内部访问其值。这个问题有可能解决吗？
根据传递的是指针还是其他类型，我需要执行一些操作，所以如果我继续递归地传递指针，程序将失败。我需要从传递的指针中获取值（而不是继续传递指针），但是因为我处理的是interface{}类型而不是指针，编译器不知道是否会传递指针，所以它不允许像*obj这样的操作来获取其值。
英文:
I'm writing a program where I need to access a value of a pointer which is passed as an interface{}.
package main
import (
"reflect"
)
type Test struct {
Names []string
}
func main() {
arr := []string{"a", "a", "a", "a", "a", "a"}
obj := new(Test)
obj.Names = arr
TestFunc(obj)
}
func TestFunc(obj interface{}){
rt := reflect.TypeOf(obj)
switch rt.Kind() {
case reflect.Struct:
return
case reflect.Ptr:
TestFunc(*obj) //<<--- There is the problem, cannot figure out how to access
//value of obj and *obj is not allowed here because of interface{} type.
}
}
This is just a sample from a much bigger program, but it is enough to explain my problem.
So the problem is, when I pass a pointer to TestFunc() I do not know how to reach its value inside function. Is it possible at all?
I need to do some stuff based on wether it is a pointer or not, so if I keep passing pointer recursively the program will fail. I need to get the value from the passed pointer(and pass forward value instead of pointer) but I am not sure if it is possible because I am dealing with a type interface{} and not a pointer and compiler does not know if it is going to be a pointer passed so it does not allow something like "*obj" to reach the value of it.
答案1
得分: 3
如果您需要支持任意级别的指针，可以使用反射来获取值对象：
v := reflect.ValueOf(obj)
for v.Kind() == reflect.Ptr {
v = v.Elem()
}
v.Interface()
然而，在实际应用中，这种情况相当不常见。
对于您的函数，可以这样实现：
func TestFunc(obj interface{}) {
rv := reflect.ValueOf(obj)
switch rv.Kind() {
case reflect.Struct:
// 在这里编写代码
return
case reflect.Ptr:
TestFunc(rv.Elem().Interface())
}
}
英文:
If you need to support arbitrary levels of pointers then you can use reflection to get the value object:
v:=reflect.ValueOf(obj)
for v.Kind() == reflect.Ptr {
v = v.Elem()
}
v.Interface()
However, this is quite unusual to actually need to do in practice.
For your function, this could work as something like:
func TestFunc(obj interface{}){
rv := reflect.ValueOf(obj)
switch rv.Kind() {
case reflect.Struct:
// code here
return
case reflect.Ptr:
TestFunc(rv.Elm().Interface())
}
}
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