英文:
Initialize embedded struct in Go
问题
我有以下的struct，其中包含一个net/http.Request：
type MyRequest struct {
http.Request
PathParams map[string]string
}
现在我想在以下函数中初始化匿名内部结构http.Request：
func New(origRequest *http.Request, pathParams map[string]string) *MyRequest {
req := new(MyRequest)
req.PathParams = pathParams
return req
}
如何使用参数origRequest初始化内部结构？
英文:
I have the following struct which contains a net/http.Request:
type MyRequest struct {
http.Request
PathParams map[string]string
}
Now I want to initialize the anonymous inner struct http.Request in the following function:
func New(origRequest *http.Request, pathParams map[string]string) *MyRequest {
req := new(MyRequest)
req.PathParams = pathParams
return req
}
How can I initialize the inner struct with the parameter origRequest?
答案1
得分: 42
req := new(MyRequest)
req.PathParams = pathParams
req.Request = origRequest
或者...
req := &MyRequest{
PathParams: pathParams
Request: origRequest
}
更多关于嵌入和字段命名的信息，请参阅：http://golang.org/ref/spec#Struct_types。
英文:
req := new(MyRequest)
req.PathParams = pathParams
req.Request = origRequest
or...
req := &MyRequest{
PathParams: pathParams
Request: origRequest
}
See: http://golang.org/ref/spec#Struct_types for more about embedding and how the fields get named.
答案2
得分: 21
func New(origRequest *http.Request, pathParams map[string]string) *MyRequest {
return &MyRequest{*origRequest, pathParams}
}
它显示，而不是
New(foo, bar)
你可能更喜欢直接使用
&MyRequest{*foo, bar}
英文:
What about:
func New(origRequest *http.Request, pathParams map[string]string) *MyRequest {
return &MyRequest{*origRequest, pathParams}
}
It shows that instead of
New(foo, bar)
you might prefer just
&MyRequest{*foo, bar}
directly.
答案3
得分: 7
正如Jeremy在上面展示的那样，匿名字段的“名称”与字段的类型相同。因此，如果x的值是包含匿名int的结构体，那么x.int将引用该字段。
英文:
As Jeremy shows above, the "name" of an anonymous field is the same as the type of the field. So if the value of x were a struct containing an anonymous int, then x.int would refer to that field.
答案4
得分: 1
只为完整起见，我还会添加另一个例子。根据@Victor的评论：
type MyRequest struct {
http.Request
PathParams map[string]string
}
func New(origRequest *http.Request, pathParams map[string]string) *MyRequest {
req := MyRequest{Request: origRequest, PathParams: pathParams}
return req
}
@Jeffery Martinez的另一个评论进一步澄清了这一点：
"The unqualified type name acts as the field name." So `http.Request` ends up being called just `Request`
即：以下两个声明是等价的
// Version 1
type MyRequest struct {
http.Request
PathParams map[string]string
}
// Version 2
type MyRequest struct {
Request http.Request
PathParams map[string]string
}
英文:
Just for completeness sake, I'll add another example as well. Based on the comment from @Victor
> This example shows another way recommended https://play.golang.org/p/Gbn8e6CTVi_c
type MyRequest struct {
http.Request
PathParams map[string]string
}
func New(origRequest *http.Request, pathParams map[string]string) *MyRequest {
req := MyRequest{Request: origRequest, PathParams: pathParams}
return req
}
Another comment from @Jeffery Martinez helped clarify it further:
> As for how the fields get named: "The unqualified type name acts as the field name." So http.Request ends up being called just Request
i.e: The two following declarations are equivalent
// Version 1
type MyRequest struct {
http.Request
PathParams map[string]string
}
// Version 2
type MyRequest struct {
Request http.Request
PathParams map[string]string
}
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