英文:
How to initialize a list of objects given only an interface sample?
问题
我正在使用Google Go编写一个数据库接口。它接受encoding.BinaryMarshaler对象进行保存，并将它们保存为[]byte切片，然后将数据加载到encoding.BinaryUnmarshaler中返回：
func (db *DB) Get(bucket []byte, key []byte, destination encoding.BinaryUnmarshaler) (encoding.BinaryUnmarshaler, error) {
我想实现一次性加载任意长度的encoding.BinaryUnmarshaler切片（例如“从桶X加载所有数据”）。我希望该函数能够加载任意数量的数据对象，而不需要事先知道要加载多少个对象，因此我不希望最终用户传递一个要填充的切片。相反，我使用一个encoding.BinaryUnmarshaler示例对象来了解我要处理的结构：
func (db *DB) GetAll(bucket []byte, sample encoding.BinaryUnmarshaler) ([]encoding.BinaryUnmarshaler, error) {
在编写代码时遇到的问题是，我不确定如何初始化给定对象的新实例，因为我不知道我正在处理的是什么对象，只知道它符合哪个接口。我尝试的方法是：
tmp := new(reflect.TypeOf(sample))
但是这只会导致错误。
在Go中，如何在不知道结构的情况下创建一个新对象，而只有一个示例对象呢？
英文:
I'm writing a database interface in Google Go. It takes encoding.BinaryMarshaler objects to save and saves them as []byte slices, and it loads data into encoding.BinaryUnmarshaler to return it:
func (db *DB) Get(bucket []byte, key []byte, destination encoding.BinaryUnmarshaler) (encoding.BinaryUnmarshaler, error) {
I want to implement being able to load an arbitrary length slice of encoding.BinaryUnmarshalers in one go (for example "load all data from a bucket X"). I want the function to be able to load any number of data objects without knowing beforehand how many objects are to be loaded, so I don't expect the final user to pass me a slice to be filled. Instead, I take a encoding.BinaryUnmarshaler sample object to know what structures I'm dealing with:
func (db *DB) GetAll(bucket []byte, sample encoding.BinaryUnmarshaler) ([]encoding.BinaryUnmarshaler, error) {
The problem I ran into while coding this, is that I'm not sure how to initialize new instances of a given object, since I don't know what object I am dealing with, only what interface it conforms to. What I tried doing was:
tmp:=new(reflect.TypeOf(sample))
but that just caused an error.
How can I create a new object in go without knowing what structure it is, having an example object instead?
答案1
得分: 1
你需要使用reflect.New和reflect.TypeOf来实现：
tmp := reflect.New(reflect.TypeOf(sample))
http://play.golang.org/p/-ujqWtRzaP
英文:
You would have to use reflect.New along with reflect.TypeOf:
tmp := reflect.New(reflect.TypeOf(sample))
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。
评论