英文:
Golang range type conversion
问题
我对我拥有的这段代码感到非常困惑：
docs, ok := foo.([]interface {})
if !ok{ panic("assertion failed") }
fmt.Println("The type of docs: ", reflect.TypeOf(docs))
for _, doc := range docs {
fmt.Println("Doc Type: ", reflect.TypeOf(doc))
}
当我运行这段代码时，输出结果是：
The type of docs: []interface {}
Doc type: bson.D
我不明白。我将foo类型断言为[]interface{}并将其存储在docs中。这符合预期，但是在循环中，我打印出的第一件事是doc的类型，它显示为bson.D。为什么不是interface {}？我甚至将doc的名称更改为bar，以为可能是作用域问题之类的，但结果还是一样的。
英文:
I'm very confused by this code that I have:
docs, ok := foo.([]interface {})
if !ok{ panic("assertion failed") }
fmt.Println("The type of docs: ", reflect.TypeOf(docs))
for _, doc := range docs {
fmt.Println("Doc Type: ", reflect.TypeOf(doc))
}
The output when I run this is:
The type of docs: []interface {}
Doc type: bson.D
I don't get it. I type assert foo to []interface{} and store it in docs. That works as expected, but then in the loop, the first thing I print out is the type of doc and it says it's bson.D. How is it not interface {}?? I even changed the name of doc to bar thinking maybe it was a scoping issue or something, but I get the same results.
答案1
得分: 3
TypeOf文档中写道：TypeOf返回interface{}中值的反射类型。TypeOf(nil)返回nil。
所以doc的类型是interface{}，但是TypeOf返回它的“真实”类型。
英文:
TypeOf documentation says: TypeOf returns the reflection Type of the value in the interface{}. TypeOf(nil) returns nil.
So doc is of type interface{} but TypeOf returns its "true" type.
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