在 Go 中，如何在运行时根据其类型创建结构的新实例? [英] How do you create a new instance of a struct from its type at run time in Go?

问题描述

在 Go 中，如何在运行时根据对象的类型创建对象的实例?我想您还需要先获取对象的实际 type 吗?

In Go, how do you create the instance of an object from its type at run time? I suppose you would also need to get the actual type of the object first too?

我正在尝试进行延迟实例化以节省内存.

I am trying to do lazy instantiation to save memory.

推荐答案

为了做到这一点，你需要 reflect.

In order to do that you need reflect.

package main

import (
    "fmt"
    "reflect"
)

func main() {
    // one way is to have a value of the type you want already
    a := 1
    // reflect.New works kind of like the built-in function new
    // We'll get a reflected pointer to a new int value
    intPtr := reflect.New(reflect.TypeOf(a))
    // Just to prove it
    b := intPtr.Elem().Interface().(int)
    // Prints 0
    fmt.Println(b)

    // We can also use reflect.New without having a value of the type
    var nilInt *int
    intType := reflect.TypeOf(nilInt).Elem()
    intPtr2 := reflect.New(intType)
    // Same as above
    c := intPtr2.Elem().Interface().(int)
    // Prints 0 again
    fmt.Println(c)
}

你可以用结构体类型而不是整数来做同样的事情.或者别的什么，真的.当涉及到 map 和 slice 类型时，请务必了解 new 和 make 之间的区别.

You can do the same thing with a struct type instead of an int. Or anything else, really. Just be sure to know the distinction between new and make when it comes to map and slice types.

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