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How to create dynamic custom types using Go’s reflection? Create a custom type: Use the type keyword to define a structure. Get the reflection type: Get the type reflection type through the reflect.TypeOf() function. Create a dynamic type: Use the reflect.New function to create a pointer to a custom type. Set values: Use the v.Elem() and reflect.Set() functions to set values. Get value: Use the Interface() method to get the interface value of the value.
How to use Go’s reflection to create dynamic custom types
Reflection is a powerful feature in Go that allows programs Inspect and modify its own code. With reflection, we can create dynamic custom types that can be modified at runtime as needed.
Create a custom type
To create a custom type, we can use the type
keyword:
type person struct { name string age int }
Reflection type
To obtain the reflection type of a type, you can use the reflect.TypeOf()
function:
t := reflect.TypeOf(person{})
Create a dynamic type
To create a dynamic type, we can use the reflect.New
function taking the specified reflection type as argument:
v := reflect.New(t)
The v
variable now represents A pointer to a custom type. We can now use reflection to set and get values:
Set the value
You can use v.Elem()
to get the value pointed to by the pointer, Then set the value using standard methods or the reflect.Set
function:
v.Elem().FieldByName("name").SetString("John") v.Elem().FieldByName("age").SetInt(30)
Get the value
Use the reflect.Value
type The Interface
method can get the interface value of the value:
name := v.Elem().FieldByName("name").Interface() age := v.Elem().FieldByName("age").Interface()
Practical case
Suppose we have a JSON string that contains a person's Name and age:
{ "name": "Jane", "age": 35 }
We can use reflection to dynamically create the person
type and set its value:
import ( "encoding/json" "fmt" "reflect" ) func main() { // 反射创建自定义类型 t := reflect.TypeOf(person{}) v := reflect.New(t) // 反射解组 JSON 字符串 var data map[string]interface{} err := json.Unmarshal([]byte(`{ "name": "Jane", "age": 35 }`), &data) if err != nil { panic(err) } // 反射设置字段值 for k, v := range data { v.Elem().FieldByName(k).Set(reflect.ValueOf(v)) } // 反射获取字段值 fmt.Println(v.Elem().FieldByName("name").Interface()) // 输出:"Jane" fmt.Println(v.Elem().FieldByName("age").Interface()) // 输出:35 } type person struct { name string age int }
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