英文:
Infer struct structure
问题
我正在使用这个来创建一个没有定义单独类型的结构体：
data := struct {
Product *domain.UserProduct
Options *[]domain.UserProductOption
}{
Product: userProduct,
Options: userProductOptions,
}
有没有一种方法可以在不定义struct的结构的情况下做到同样的事情，因为字段的数量和类型可以被推断出来？类似这样：
data := {
Product: userProduct,
Options: userProductOptions,
}
英文:
I am using this to create a struct without defining a separate type:
data := struct {
Product *domain.UserProduct
Options *[]domain.UserProductOption
}{
Product: userProduct,
Options: userProductOptions,
}
Is there a way to do the same without defining struct's structure, as number of fields and their types can inferred? Something like:
data := {
Product: userProduct,
Options: userProductOptions,
}
答案1
得分: 2
截至Go 1.17版本，还没有类似的方法来推断结构体的类型。
在提案#35304中对此进行了一些讨论，但目前还没有确定。总结一下讨论的内容：
foo({x: y})- 难以阅读data := _{x: y}- 难以阅读 (?)data := struct {x: y}- 过载了struct的语法data := tuple {x: y}- 新的关键字- . . .
欢迎您参与讨论，或者提交您自己的提案。
我认为像data := struct _ {X: x, Y: y}这样的写法应该最符合使用_来省略内容的哲学（在这种情况下，我们希望省略结构体定义）。
英文:
As of Go 1.17 there's nothing like that to infer the type of a struct.
There's been some discussion of this in the proposal #35304, but it's still open. To summarize the discussion:
foo({x: y})- unreadabledata := _{x: y}- unreadable (?)data := struct {x: y}- overloads the syntax ofstructdata := tuple {x: y}- new keyword- . . .
You're welcome to participate in the discussion and/or submit your own proposal.
I would think something like data := struct _ {X: x, Y: y} should be the most in line with the philosophy of _ being used to omit things (as in this case we want to omit the struct definition).
答案2
得分: 1
没有。该语言不允许这样做：在复合字面量中，定义了它们的工作原理：
复合字面量用于构造结构体、数组、切片和映射的值，并在每次评估时创建一个新值。**它们由字面量的类型后跟一个用大括号括起来的元素列表组成。**每个元素可以选择由相应的键前导。
CompositeLit = LiteralType LiteralValue .
LiteralType = StructType | ArrayType | "[" "..." "]" ElementType |
SliceType | MapType | TypeName .
LiteralValue = "{" [ ElementList [ "," ] ] "}" .
可以使用字面量值的地方是在元素列表中：
// 结构体类型可以是定义的或字面量
// 定义的类型
type User struct {
Name string
}
// `{ "John" }` 是字面量值
foo := []User{{ "John" }}
// 字面量类型
// `{ "John", "john@myself.com" }` 是字面量值
bar := []struct{Name string; Email string}{{ "John", "john@myself.com" }}
英文:
> Is there a way to do the same without defining struct's structure
No. The language doesn't allow it: in Composite literals, it is defined how these work:
> Composite literals construct values for structs, arrays, slices, and maps and create a new value each time they are evaluated. They consist of the type of the literal followed by a brace-bound list of elements. Each element may optionally be preceded by a corresponding key.
CompositeLit = LiteralType LiteralValue .
LiteralType = StructType | ArrayType | "[" "..." "]" ElementType |
SliceType | MapType | TypeName .
LiteralValue = "{" [ ElementList [ "," ] ] "}" .
The place where you can have the literal value is in an element list:
// the struct type may be defined or literal
// defined type
type User struct {
Name string
}
// `{"John"}` is the literal value
foo := []User{{"John"}}
// literal type
// `{"John","john@myself.com"}` is the literal value
bar := []struct{Name string; Email string}{{"John","john@myself.com"}}
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