英文:
How to store predefined instances of a struct in a way that they can be referenced by name?
问题
我想存储许多预定义实例的结构体作为常量，并以一种能够通过名称引用它们的方式进行分组。
我可以这样实现：
use std::collections::HashMap;struct MyStruct {// ...}const INSTANCES: HashMap<&str, MyStruct> = [("Instance1", MyStruct {// fields...}),("Instance2", MyStruct {// fields...}),("Instance3", MyStruct {// fields...}),// 添加更多实例，根据需要].iter().cloned().collect();fn main() {let instance = INSTANCES.get("Instance1");// ...}
或者这样：
struct MyStruct {// ...}enum MyStructInstance {Instance1,Instance2,Instance3,// 根据需要添加更多实例}impl MyStructInstance {fn get_instance(&self) -> MyStruct {match self {MyStructInstance::Instance1 => MyStruct {// fields...},MyStructInstance::Instance2 => MyStruct {// fields...},MyStructInstance::Instance3 => MyStruct {// fields...},// ...}}}fn main() {let instance1 = MyStructInstance::Instance1.get_instance();// ...}
但似乎不够规范。存储预定义实例的命名列表的标准方式是什么？
英文:
I would like to store many predefined instances of a struct as constants and group them in a way that I am able to reference them by name.
I could achieve it like this:
use std::collections::HashMap;struct MyStruct {// ...}const INSTANCES: HashMap<&str, MyStruct> = [("Instance1", MyStruct {// fields...}),("Instance2", MyStruct {// fields...}),("Instance3", MyStruct {// fields...}),// Add more instances as needed].iter().cloned().collect();fn main() {let instance = INSTANCES.get("Instance1");// ...}
Or this:
struct MyStruct {// ...}enum MyStructInstance {Instance1,Instance2,Instance3,// Add more instances as needed}impl MyStructInstance {fn get_instance(&self) -> MyStruct {match self {MyStructInstance::Instance1 => MyStruct {// fields...},MyStructInstance::Instance2 => MyStruct {// fields...},MyStructInstance::Instance3 => MyStruct {// fields...},// ...}}}fn main() {let instance1 = MyStructInstance::Instance1.get_instance();// ...}
But it does not seem well formed. What is the standard way for storing a named list of predefined instances?
答案1
得分: 1
我想将许多预定义的结构实例存储为 常量 并以一种方式 分组，以便我能够通过 名称 对它们进行 引用。
pub mod group {pub struct MyStruct {// ...}pub const Instance1: MyStruct = MyStruct {};pub const Instance2: MyStruct = MyStruct {};pub const Instance3: MyStruct = MyStruct {};}fn main() {let instance1 = group::Instance1;let instance2 = group::Instance2;// ...}
英文:
> I would like to store many predefined instances of a struct as constants and group them in a way that I am able to reference them by name.
pub mod group {pub struct MyStruct {// ...}pub const Instance1: MyStruct = MyStruct {};pub const Instance2: MyStruct = MyStruct {};pub const Instance3: MyStruct = MyStruct {};}fn main() {let instance1 = group::Instance1;let instance2 = group::Instance2;// ...}
Playground. If you want to modify them, you can use static with unsafe updates. You may implement FromStr trait for MyStruct, if you need conversions from strings.
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