英文:
In Go, what's the inverse of reflect.SliceOf()?
问题
在Go语言中，reflect.SliceOf()函数可以创建一个表示给定类型切片的Type对象：
> SliceOf返回具有元素类型t的切片类型。例如，如果t表示int，那么SliceOf(t)表示[]int。
然而，我已经有一个[]int的Type对象，但我想要得到一个int的Type对象。有没有简单的方法可以做到这一点？（注意，我以int作为示例。实际上，我只知道我有一个切片，我需要找到切片中每个元素的类型。）
我正在尝试使用反射从[]string中填充一个bool、int、float或string类型的切片...下面是相关的代码片段：
numElems := len(req.Form["keyName"])
if structField.Kind() == reflect.Slice && numElems > 0 {
slice := reflect.MakeSlice(structField.Type(), numElems, numElems)
for i := 0; i < numElems; i++ {
// 这里还有一些其他的代码来填充切片
}
}
但是为了填充切片，我需要知道正在填充的切片的类型...
英文:
In Go, reflect.SliceOf() makes a Type representing a slice of the given Type:
> SliceOf returns the slice type with element type t. For example, if t represents int, SliceOf(t) represents []int.
However, I already have a Type for []int but want to get a Type for int. Is there an easy way to do that? (Note, I'm using int as an example. In reality, all I know is I have a slice, and I need to find what Type each element of the slice is.)
I'm trying to populate a slice of bool, int, float, or string, from a []string using reflection... here's the relevant piece:
numElems := len(req.Form["keyName"])
if structField.Kind() == reflect.Slice && numElems > 0 {
slice := reflect.MakeSlice(structField.Type(), numElems, numElems)
for i := 0; i < numElems; i++ {
// I have some other code here to fill out the slice
}
}
But in order to fill out the slice, I need to know the type of the slice I'm filling out...
答案1
得分: 5
在你的情况下，你已经有了元素类型：structField.Type()。你可以使用reflect.New(t).Elem()来获取一个可编辑的reflect.Value类型。一旦你填充了该值，你可以调用slice.Index(i).Set(...)将该值分配到结果切片中。
然而，为了回答你的问题，如果你有一个切片并且需要填充它，比如你有一个[]int的reflect.Type，那么你可以调用.Elem()来获取int的reflect.Type。
请参阅Type文档，了解可以在Type上调用的方法。
英文:
In your case, you already have the element type: structField.Type(). You can use reflect.New(t).Elem() to get an "editable" reflect.Value of a type. Once you've populated that value, you can call slice.Index(i).Set(...) to assign that value into the resulting slice.
To answer the letter of your question though, if you do have a slice and need to populate it, say you have a reflect.Type of a []int, then you can call .Elem() to get the reflect.Type for int.
See the Type documentation for the methods you can call on a Type.
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