{"id":45273,"date":"2022-11-02T17:26:34","date_gmt":"2024-01-15T15:31:41","guid":{"rendered":"https:\/\/www.silicloud.com\/zh\/blog\/45273-2\/"},"modified":"2024-04-28T22:37:20","modified_gmt":"2024-04-28T14:37:20","slug":"45273-2","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/zh\/blog\/45273-2\/","title":{"rendered":""},"content":{"rendered":"

\u6982\u8981<\/h1>\n

Rust\u3067\u30c8\u30ec\u30fc\u30c8\u30e1\u30bd\u30c3\u30c9\u306basync\u304c\u4f7f\u3048\u306a\u3044\u304c\u3001\u4f7f\u3048\u306a\u3044\u7406\u7531\u3068\u3001\u4ee3\u308f\u308a\u306b\u3067\u304d\u308b\u3053\u3068\u3092\u89e3\u8aac\u3057\u307e\u3059\u3002<\/p>\n

async traits\u3068\u306f<\/h1>\n

Rust\u306b\u975e\u540c\u671f\u51e6\u7406\u306e\u6587\u6cd5\u304c\u6b63\u898f\u3067\u5c0e\u5165\u3055\u308c\u308b\u524d\u304b\u3089\u3082\u3001\u30c8\u30ec\u30fc\u30c8\u306e\u5b9a\u7fa9\u306b\u975e\u540c\u671f\u30e1\u30bd\u30c3\u30c9\u304c\u66f8\u3051\u308b\u3088\u3046\u306b\u3057\u3066\u3082\u3089\u3044\u305f\u3044\u3068\u3044\u3046\u8981\u671b\u304c\u9577\u304f\u3042\u308a\u307e\u3059\u3002<\/p>\n

\u30c8\u30ec\u30fc\u30c8\u306b\u975e\u540c\u671f\u306e\u30e1\u30bd\u30c3\u30c9\u5b9a\u7fa9\u306f\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u69cb\u6587\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n

trait<\/span> MyAsyncTrait<\/span> {<\/span>\r\n  async<\/span> fn<\/span> answer<\/span>(<\/span>&<\/span>self<\/span>)<\/span> -><\/span> usize<\/span>;<\/span>\r\n}<\/span>\r\n\r\nstruct<\/span> Life<\/span>(<\/span>usize<\/span>);<\/span>\r\n\r\nimpl<\/span> MyAsyncTrait<\/span> for<\/span> Life<\/span> {<\/span>\r\n  async<\/span> fn<\/span> answer<\/span>(<\/span>&<\/span>self<\/span>)<\/span> -><\/span> usize<\/span> {<\/span>\r\n    self<\/span>.0<\/span>\r\n  }<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u3057\u304b\u3057\u3001\u6295\u7a3f\u6642\u306e\u30b9\u30c6\u30fc\u30d6\u30ebRust\u3067\u306f\u3001\u4e0a\u8a18\u306e\u30b3\u30fc\u30c9\u306f\u30b3\u30f3\u30d1\u30a4\u30eb\u3055\u308c\u305a\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u30a8\u30e9\u30fc\u304c\u51fa\u529b\u3055\u308c\u307e\u3059\u3002<\/p>\n
functions in traits cannot be declared `async`\r\n`async` trait functions are not currently supported\r\nconsider using the `async-trait`\r\n<\/code><\/pre>\n
aysync-trait\u306b\u3064\u3044\u3066\u306f\u5f8c\u3005\u89e6\u308c\u307e\u3059\u304c\u3001\u306a\u305c\u3053\u306e\u3088\u3046\u306a\u3054\u304f\u7c21\u5358\u306b\u898b\u3048\u308b\u3053\u3068\u304c\u3067\u304d\u306a\u3044\u306e\u3060\u308d\u3046\u304b\uff1fasync {}\u306e\u975e\u540c\u671f\u30d6\u30ed\u30c3\u30af\u3068async fn foo() {}\u306a\u3089\u554f\u984c\u306a\u304fRust\u306e\u30b3\u30f3\u30d1\u30a4\u30eb\u304c\u53d7\u3051\u4ed8\u3051\u3066\u304f\u308c\u308b\u306e\u306b\u3001\u306a\u305c\u30c8\u30ec\u30fc\u30c8\u306b\u306a\u308b\u3068\u3001\u6025\u306b\u5f31\u8170\u306b\u306a\u308b\u306e\u3060\u308d\u3046\u304b\uff1f<\/p>\n
\u5b9f\u306f\u6df1\u3044\u8a33\u304c\u3042\u308b\u306e\u3067\u3059\u3002<\/p>\n
Rust\u306b\u304a\u3051\u308b\u30c8\u30ec\u30a4\u30c8\u306e\u52d5\u7684\u30c7\u30a3\u30b9\u30d1\u30c3\u30c1<\/h1>\n
\u3044\u3063\u305f\u3093\u975e\u540c\u671f\u306f\u508d\u306b\u7f6e\u3044\u3066\u3001\u52d5\u7684\u30c7\u30a3\u30b9\u30d1\u30c3\u30c1\u306b\u3064\u3044\u3066\u8a71\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n
Rust\u306b\u306f\u3001\u30b8\u30a7\u30cd\u30ea\u30c3\u30af\u578b\u306e\u5ef6\u9577\u7dda\u3067\u300c\u3053\u306e\u30c8\u30ec\u30fc\u30c8\u3092\u5b9f\u88c5\u3057\u3066\u3044\u308c\u3070\u3001\u3069\u3093\u306a\u578b\u3067\u3082\u3044\u3044\u3088\u300d\u3068\u3044\u3046\u8a18\u6cd5\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n
trait<\/span> Greetable<\/span> {<\/span>\r\n    fn<\/span> greet<\/span>(<\/span>&<\/span>self<\/span>);<\/span>\r\n}<\/span>\r\n\r\nfn<\/span> call_greet<\/span>(<\/span>o<\/span>:<\/span> &<\/span>dyn<\/span> Greetable<\/span>)<\/span> {<\/span>\r\n    o<\/span>.greet<\/span>();<\/span>\r\n}<\/span>\r\n\r\nstruct<\/span> Foo<\/span> {}<\/span>\r\n\r\nimpl<\/span> Greetable<\/span> for<\/span> Foo<\/span> {<\/span>\r\n    fn<\/span> greet<\/span>(<\/span>&<\/span>self<\/span>)<\/span> {<\/span>\r\n        println!<\/span>(<\/span>\"hello world, from Foo.\"<\/span>);<\/span>\r\n    }<\/span>\r\n}<\/span>\r\n\r\nfn<\/span> main<\/span>()<\/span> {<\/span>\r\n    let<\/span> foo<\/span> =<\/span> Foo<\/span> {};<\/span>\r\n\r\n    call_greet<\/span>(<\/span>&<\/span>foo<\/span>);<\/span> \/\/ hello world, from Foo.<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u3053\u306e\u8a18\u6cd5\u3092\u52d5\u7684\u30c7\u30a3\u30b9\u30d1\u30c3\u30c1\u3068\u8a00\u308f\u308c\u3066\u304a\u308a\u3001\u3069\u306estruct\u3067\u3082Greetable\u3092\u5b9f\u88c5\u3057\u3066\u3044\u308c\u3070\u5f15\u6570\u3068\u3057\u3066\u306e\u6761\u4ef6\u3092\u6e80\u305f\u3059\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n
\u8907\u6570\u306eGreetable\u3092\u5b9f\u88c5\u3057\u3066\u3044\u308b\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u5f15\u6570\u306b\u3059\u308b\u3053\u3068\u3082\u3067\u304d\u307e\u3059\u3002<\/p>\n
fn<\/span> greet_all<\/span>(<\/span>objects<\/span>:<\/span> &<\/span>[<\/span>&<\/span>dyn<\/span> Greetable<\/span>])<\/span> {<\/span>\r\n    for<\/span> obj<\/span> in<\/span> objects<\/span> {<\/span>\r\n        obj<\/span>.greet<\/span>();<\/span>\r\n    }<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u3055\u3089\u306bBar\u3068\u3044\u3046struct\u3092\u5b9a\u7fa9\u3057\u3066\u3082\u540c\u69d8\u306b\u4f7f\u3048\u307e\u3059\u3002<\/p>\n
struct<\/span> Bar<\/span> {}<\/span>\r\n\r\nimpl<\/span> Greetable<\/span> for<\/span> Bar<\/span> {<\/span>\r\n    fn<\/span> greet<\/span>(<\/span>&<\/span>self<\/span>)<\/span> {<\/span>\r\n        println!<\/span>(<\/span>\"hello world, from Bar.\"<\/span>);<\/span>\r\n    }<\/span>\r\n}<\/span>\r\n\r\nfn<\/span> main<\/span>()<\/span> {<\/span>\r\n    let<\/span> foo<\/span> =<\/span> Foo<\/span> {};<\/span>\r\n    let<\/span> bar<\/span> =<\/span> Bar<\/span> {};<\/span>\r\n\r\n    call_greet<\/span>(<\/span>&<\/span>foo<\/span>);<\/span> \/\/ hello world, from Foo.<\/span>\r\n    call_greet<\/span>(<\/span>&<\/span>bar<\/span>);<\/span>\r\n    greet_all<\/span>(<\/span>&<\/span>vec!<\/span>[<\/span>&<\/span>foo<\/span>,<\/span> &<\/span>bar<\/span>]);<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u52d5\u7684\u30c7\u30a3\u30b9\u30d1\u30c3\u30c1\u3068vtable\u306e\u95a2\u4fc2<\/h2>\n
\u4e0a\u8a18\u306e\u30ed\u30b8\u30c3\u30af\u3092\u898b\u3066\u3001\u8aad\u8005\u306f\u3042\u308b\u3044\u306f\u300c\u306a\u305ccall_greet\u306f\u9055\u3046struct\u3067\u3082\u3069\u3053\u306b\u305d\u306e\u30e1\u30bd\u30c3\u30c9\u304c\u3042\u308b\u306e\u304b\u3092\u77e5\u308c\u308b\u3093\u3060\u308d\u3046\u300d\u3068\u9996\u3092\u50be\u3052\u308b\u306e\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u3002\u3042\u308b\u3044\u306f\u30b3\u30f3\u30d1\u30a4\u30e9\u30fc\u306e\u9b54\u6cd5\u3092\u4fe1\u3058\u308b\u3053\u3068\u306b\u3059\u308b\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u3002<\/p>\n
\u524d\u8005\u306e\u304a\u76f8\u624b\u3092\u3057\u305f\u3044\u306e\u3067\u3059\u304c\u3001\u52d5\u7684\u30c7\u30a3\u30b9\u30d1\u30c3\u30c1\u306f\u307e\u3055\u306b\u305d\u306e\u3053\u3068\u3067\u3042\u308a\u3001\u5b9f\u884c\u6642\u306b\u540c\u30c8\u30ec\u30fc\u30c8\u3092\u5b9f\u88c5\u3057\u3066\u3044\u308bFoo\u3068Bar\u306e\u3069\u3053\u3092\u3069\u3046\u3059\u308c\u3070call_greet\u304c\u547c\u3079\u308b\u306e\u304b\u306f\u3001vtable\u3068\u3044\u3046\u3082\u306e\u3092\u53c2\u7167\u3057\u3066::greet\u3068::greet`\u306e\u30e1\u30e2\u30ea\u4e0a\u306b\u304a\u3051\u308b\u3042\u308a\u304b\u3092\u8abf\u3079\u3089\u308c\u308b\u304b\u3089\u3067\u3059\u3002<\/p>\n
dyn Greetable\u306e\u3088\u3046\u306a\u52d5\u7684\u30b8\u30a7\u30cd\u30ea\u30c3\u30af\u3092\u4f7f\u3063\u305f\u6642\u306b\u3001\u5b9f\u306f\u30b3\u30f3\u30d1\u30a4\u30e9\u30fc\u304c\u88cf\u3067\u914d\u7dda\u56f3\u306b\u306a\u308bvtable\u3092\u751f\u6210\u3057\u3066\u304f\u308c\u3066\u3044\u308b\u306e\u3067\u3059\u3002\u4f8b\u3048\u3070\u4e0a\u8a18\u306eFoo\u3068Bar\u3060\u3068\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u3000vtable\u304c\u751f\u6210\u3055\u308c\u307e\u3059\uff1a<\/p>\n
struct<\/span> Foo_Greetable_123123<\/span><<\/span>'a<\/span>><\/span> {<\/span>\r\n    greet<\/span>:<\/span> &<\/span>'a<\/span> fn<\/span>(<\/span>&<\/span>'a<\/span> Foo<\/span>),<\/span>\r\n}<\/span>\r\n\r\nstruct<\/span> Bar_Greetable_038484<\/span><<\/span>'a<\/span>><\/span> {<\/span>\r\n    greet<\/span>:<\/span> &<\/span>'a<\/span> fn<\/span>(<\/span>&<\/span>'a<\/span> Bar<\/span>),<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u4e0a\u8a18\u306evtable\u306f\u3001\u5b9f\u884c\u6642\u306b\u306f\u52d5\u7684\u306b\u4f7f\u3063\u3066\u3044\u308bdyn FooBar\u306e\u30dd\u30a4\u30f3\u30bf\u30fc\u306b\u88cf\u3067\u304f\u3063\u4ed8\u3051\u3089\u308c\u3066\u3001\u300c\u30d5\u30a1\u30c3\u30c8\u30dd\u30a4\u30f3\u30bf\u30fc\u300d\u3068\u3044\u3046\u3082\u306e\u306b\u306a\u308a\u307e\u3059\u3002\u3064\u307e\u308a\u3001call_greet(&foo);\u306b\u304a\u3051\u308b&foo\u306f\u305f\u3060\u5358\u306bFoo\u3078\u306e\u30dd\u30a4\u30f3\u30bf\u3060\u3051\u3067\u306a\u304f\u3001Foo\u306b\u3082\u3001Foo_Greetable_123123\u306b\u3082\u53c2\u7167\u3092\u6301\u3063\u3066\u3044\u308b\u306e\u3067\u3059\u3002<\/p>\n
\u4e0a\u8a18\u306e\u3088\u3046\u306a\u30d5\u30a1\u30c3\u30c8\u30dd\u30a4\u30f3\u30bf\u304c\u3042\u308b\u304b\u3089\u3001\u305f\u3068\u3048struct\u304c\u9055\u3048\u3069\u3001\u3069\u3053\u3092\u898b\u308c\u3070\u547c\u3073\u305f\u3044\u95a2\u6570(greet)\u304c\u3042\u308b\u306e\u304b\u3001\u5b9f\u884c\u6642\u306b\u308f\u304b\u308a\u307e\u3059\u3002<\/p>\n
\u52d5\u7684\u30c7\u30a3\u30b9\u30d1\u30c3\u30c1\u306e\u5927\u304d\u306a\u5236\u7d04<\/h2>\n
\u5c11\u3057\u305a\u3064\u8a71\u3092\u307e\u3068\u3081\u3066\u975e\u540c\u671f\u30c8\u30ec\u30fc\u30c8\u306b\u623b\u3057\u305f\u3044\u306e\u3067\u3059\u304c\u3001\u52d5\u7684\u30c7\u30a3\u30b9\u30d1\u30c3\u30c1\u306e\u4ed5\u7d44\u307f\u3092\u5c11\u3057\u7406\u89e3\u3057\u305f\u4eca\u3001\u305d\u306e\u4ed5\u7d44\u307f\u306e\u5236\u7d04\u306b\u3064\u3044\u3066\u89e6\u308c\u305f\u3044\u306e\u3067\u3059\u3002<\/p>\n
\u52d5\u7684\u30c7\u30a3\u30b9\u30d1\u30c3\u30c1\u306b\u306f\u3001\u30b8\u30a7\u30cd\u30ea\u30c3\u30af\u306e\u5f15\u6570\u304c\u4f7f\u3048\u306a\u3044\u306e\u3067\u3059\u3002<\/p>\n
\u4f8b\u3048\u3070\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u30e1\u30bd\u30c3\u30c9\u3092Greetable\u306b\u8ffd\u52a0\u3057\u305f\u3089\u30b3\u30f3\u30d1\u30a4\u30e9\u30fc\u304c\u3054\u7acb\u8179\u306b\u3002<\/p>\n
trait<\/span> Greetable<\/span> {<\/span>\r\n    fn<\/span> greet<\/span>(<\/span>&<\/span>self<\/span>);<\/span>\r\n\r\n    fn<\/span> greet_with_name<\/span><<\/span>T<\/span>><\/span>(<\/span>&<\/span>self<\/span>,<\/span> name<\/span>:<\/span> &<\/span>T<\/span>)<\/span>\r\n    where<\/span>\r\n        T<\/span>:<\/span> std<\/span>::<\/span>fmt<\/span>::<\/span>Display<\/span>;<\/span>\r\n}<\/span>\r\n\r\nfn<\/span> call_greet<\/span>(<\/span>o<\/span>:<\/span> &<\/span>dyn<\/span> Greetable<\/span>)<\/span> {<\/span>\r\n    o<\/span>.greet_with_name<\/span>(<\/span>\"Austin\"<\/span>);<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u30b3\u30f3\u30d1\u30a4\u30e9\u30fc\u306e\u30a8\u30e9\u30fc\u306f\u4ee5\u4e0b\u306e\u901a\u308a\u3067\u3059\u3002<\/p>\n
the trait `Greetable` cannot be made into an object\r\nfor a trait to be \"object safe\" it needs to allow building a vtable to allow the call to be resolvable dynamically\r\n<\/code><\/pre>\n
\u300cobject safe\u300d\u3068\u3044\u3046\u306e\u304c\u30ad\u30fc\u30ef\u30fc\u30c9\u3067\u3059\u304c\u3001\u5f15\u6570\u306b\u30b8\u30a7\u30cd\u30ea\u30c3\u30af\u3092\u8ffd\u52a0\u3057\u305f\u3053\u3068\u3067\u3001\u6025\u306bGreetable\u304c\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30bb\u30fc\u30d5\u3058\u3083\u306a\u304f\u306a\u3063\u305f\u306e\u3067\u3059\u306d\u3002<\/p>\n
\u3053\u308c\u306fRust\u306emonomorphization\u3068\u3044\u3046\u6a5f\u80fd\u304c\u539f\u56e0\u3067\u3042\u3063\u3066\u30b8\u30a7\u30cd\u30ea\u30c3\u30af\u95a2\u6570\u3092\u30b3\u30f3\u30d1\u30a4\u30eb\u6642\u306b\u5b9f\u969b\u306b\u4f7f\u308f\u308c\u3066\u3044\u308b\u578b\u306b\u5177\u73fe\u5316\u3059\u308b\u4ed5\u7d44\u307f\u306e\u3053\u3068\u3067\u3059\u3002<\/p>\n
\u4f8b\u3048\u3070\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306b::great_with_name\u306eT\u3092String\u3068usize\u306b\u5177\u73fe\u5316\u3057\u305f\u3089\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u30e1\u30bd\u30c3\u30c9\u304c\u30b3\u30f3\u30d1\u30a4\u30e9\u306b\u3088\u3063\u3066\u751f\u6210\u3055\u308c\u307e\u3059\uff1a<\/p>\n
impl<\/span> Greetable<\/span> {<\/span>\r\n    fn<\/span> greet_with_name_string<\/span>(<\/span>&<\/span>self<\/span>,<\/span> name<\/span>:<\/span> &<\/span>String<\/span>)<\/span> {<\/span>...<\/span>}<\/span>\r\n\r\n    fn<\/span> greet_with_name_usize<\/span>(<\/span>&<\/span>self<\/span>,<\/span> name<\/span>:<\/span> &<\/span>usize<\/span>)<\/span> {<\/span>...<\/span>}<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u3055\u3089\u306b\u3001\u3053\u306e\u62e1\u5f35\u3055\u308c\u305fGreetable\u306e\u5b9f\u88c5\u304b\u3089vtable\u3092\u4f5c\u308d\u3046\u3068\u3059\u308b\u3068\u3001\u8907\u96d1\u306b\u306a\u3063\u3066\u304d\u307e\u3059\u3002<\/p>\n
struct<\/span> Foo_Greetable_038484<\/span><<\/span>'a<\/span>><\/span> {<\/span>\r\n    greet<\/span>:<\/span> &<\/span>'a<\/span> fn<\/span>(<\/span>&<\/span>Foo<\/span>),<\/span>\r\n    greet_with_name_string<\/span>:<\/span> &<\/span>'a<\/span> fn<\/span>(<\/span>&<\/span>'a<\/span> Foo<\/span>,<\/span> name<\/span>:<\/span> &<\/span>'a<\/span> String<\/span>),<\/span>\r\n    greet_with_name_usize<\/span>:<\/span> &<\/span>'a<\/span> fn<\/span>(<\/span>&<\/span>'a<\/span> Foo<\/span>,<\/span> name<\/span>:<\/span> &<\/span>'a<\/span> usize<\/span>),<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u5b9f\u969b\u3001\u52d5\u7684\u30c7\u30a3\u30b9\u30d1\u30c3\u30c1\u3067\u3069\u306e\u3088\u3046\u306a\u7d44\u307f\u5408\u308f\u305b\u304c\u5fc5\u8981\u306a\u306e\u304b\u3001\u30b3\u30f3\u30d1\u30a4\u30e9\u30fc\u306b\u306f\u8a08\u308a\u77e5\u308c\u306a\u3044\u306e\u3067\u3001\u4eca\u73fe\u5728\u306eRust\u3067\u306f\u3053\u306e\u3088\u3046\u306avtable\u751f\u6210\u304c\u4e0d\u53ef\u80fd\u306a\u306e\u3067\u3059\u3002\u3057\u305f\u304c\u3063\u3066\u3001\u3053\u306e\u3088\u3046\u306a\u30b8\u30a7\u30cd\u30ea\u30c3\u30af\u3092\u4f7f\u3063\u305f\u95a2\u6570\u3092\u30c8\u30ec\u30fc\u30c8\u306b\u8ffd\u52a0\u3059\u308b\u3068\u3001\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30bb\u30fc\u30d5\u3058\u3083\u306a\u3044\u3068\u8a00\u308f\u308c\u307e\u3059\u3002<\/p>\n
\u52d5\u7684\u30c7\u30a3\u30b9\u30d1\u30c3\u30c1\u3068\u975e\u540c\u671f\u30c8\u30ec\u30fc\u30c8\u306e\u95a2\u4fc2<\/h1>\n
\u4e0a\u8a18\u306evtable\u751f\u6210\u306e\u5236\u7d04\u3092\u77e5\u3063\u305f\u4e0a\u3067\u3001\u305d\u308c\u304c\u975e\u540c\u671f\u30c8\u30ec\u30fc\u30c8\u306e\u5b9f\u73fe\u3068\u4f55\u306e\u95a2\u4fc2\u304c\u3042\u308b\u306e\u304b\u8003\u3048\u3066\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n
\u307e\u305a\u3001\u4ee5\u4e0b\u306efut\u306e\u578b\u306f\u4f55\u306b\u306a\u308b\u306e\u3067\u3057\u3087\u3046\u304b\uff1f<\/p>\n
let<\/span> fut<\/span> =<\/span> async<\/span> {<\/span> 42<\/span> };<\/span>\r\n<\/code><\/pre>\n
\u5b9f\u306f\u3001async\u30d6\u30ed\u30c3\u30af\u306f\u3001impl Future\u3068\u3044\u3046\u3001\u52d5\u7684\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u8fd4\u3057\u3066\u3044\u305f\u306e\u3067\u3059\u3002Future\u3068\u3044\u3046Rust\u306e\u975e\u540c\u671f\u30ed\u30b8\u30c3\u30af\u306b\u304a\u3051\u308bPromise\u306f\u30c8\u30ec\u30fc\u30c8\u306b\u904e\u304e\u305a\u3001\u975e\u540c\u671f\u51e6\u7406\u306b\u4f7f\u308f\u308c\u3066\u3044\u308b\u3059\u3079\u3066\u306e\u3082\u306e\u306f\u52d5\u7684\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306b\u306a\u3063\u3066\u3044\u307e\u3059\u3002\u4e0a\u8a18\u306easync\u30d6\u30ed\u30c3\u30af\u306f\u5b9f\u306f\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u578b\u304c\u3064\u3044\u3066\u3044\u307e\u3059\u3002<\/output><\/p>\n
let<\/span> fut<\/span>:<\/span> impl<\/span> Future<\/span><<\/span>Output<\/span> =<\/span> i32<\/span>><\/span> =<\/span> async<\/span> {<\/span> 42<\/span> };<\/span>\r\n<\/code><\/pre>\n
impl Future\u306f\u52d5\u7684\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3067\u3001\u30b3\u30f3\u30d1\u30a4\u30eb\u6642\u306b\u30b5\u30a4\u30ba\u304c\u308f\u304b\u308a\u307e\u305b\u3093\u3002\u4f8b\u3048\u3070\u3001fut\u306e\u3088\u3046\u306a\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u30c8\u30ec\u30fc\u30c8\u306e\u30e1\u30bd\u30c3\u30c9\u306e\u623b\u308a\u5024\u306b\u3057\u305f\u3089\u3001\u30b3\u30f3\u30d1\u30a4\u30eb\u3055\u305b\u3066\u304f\u308c\u307e\u305b\u3093\u3002<\/output><\/p>\n
trait<\/span> Greetable<\/span> {<\/span>\r\n    fn<\/span> greet<\/span>(<\/span>&<\/span>self<\/span>);<\/span>\r\n\r\n    fn<\/span> greet_async<\/span>(<\/span>&<\/span>self<\/span>)<\/span> -><\/span> impl<\/span> Future<\/span><<\/span>Output<\/span> =<\/span> i32<\/span>><\/span>;<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u30a8\u30e9\u30fc\u306e\u5185\u5bb9\u306f\u4ee5\u4e0b\u306e\u901a\u308a\u3067\u3059\u3002<\/p>\n
`impl Trait` only allowed in function and inherent method return types, not in trait method return types\r\n<\/code><\/pre>\n
\u3053\u308c\u306f\u5148\u307b\u3069\u306evtable\u3068\u3082\u3001Monomorphization\u3068\u3082\u95a2\u4fc2\u304c\u3042\u308a\u307e\u3059\uff1basync fn\u3068async\u30d6\u30ed\u30c3\u30af\u304c\u8fd4\u3057\u3066\u3044\u308b\u306e\u306f\u3001\u8a00\u3048\u3070\u30b8\u30a7\u30cd\u30ea\u30c3\u30af\u30bf\u30a4\u30d7\u306a\u306e\u3067\u3059\u3002\u4e0a\u8a18\u306egreet_async\u3092\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u8003\u3048\u308c\u3070\u660e\u78ba\u3067\u3059\u3002<\/p>\n
trait<\/span> Greetable<\/span> {<\/span>\r\n    ...<\/span>\r\n\r\n    fn<\/span> greet_async<\/span><<\/span>T<\/span>><\/span>(<\/span>&<\/span>self<\/span>)<\/span> -><\/span> T<\/span> where<\/span> T<\/span>:<\/span> Future<\/span><<\/span>Output<\/span> =<\/span> i32<\/span>><\/span>;<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u3053\u308c\u304cMonomorphization\u3068vtable\u304c\u76f8\u6027\u60aa\u304f\u3076\u3064\u304b\u3063\u3066\u3057\u307e\u3046\u5236\u7d04\u306a\u306e\u3067\u3059\u3002\u3064\u307e\u308a\u3001Future\u3092\u6301\u3063\u3066\u3001\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u30bb\u30fc\u30d5\u306avtable\u3092\u751f\u6210\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u306a\u3044\u306e\u3067\u3059\u3002<\/output><\/p>\n
\u3058\u3083\u3042\u3001\u305d\u3082\u305d\u3082dyn\u3092\u4f7f\u308f\u306a\u3044\u3067\u3001\u305a\u3063\u3068impl Future\u3092\u4f7f\u3048\u3070\u3044\u3044\u306e\u3067\u306f\uff1f\u3068\u601d\u3046\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u304c\u3001\u5b9f\u306f\u30b3\u30f3\u30d1\u30a4\u30e9\u30fc\u304c\u751f\u6210\u3057\u3066\u304f\u308c\u308bFuture\u30c8\u30ec\u30fc\u30c8\u306e\u5b9f\u88c5\u306b\u306f\u6df1\u3044\u3001\u6df1\u3044\u8a33\u304c\u3042\u3063\u3066\u3001async fn\u3082\u3057\u304f\u306fasync\u30d6\u30ed\u30c3\u30af\u306f\u5fc5\u305a\u52d5\u7684\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306b\u5909\u63db\u3055\u308c\u306a\u3044\u3068\u3044\u3051\u306a\u3044\u306e\u3067\u3059\u3002<\/p>\n
\u306a\u305casync fn\u3068async\u30d6\u30ed\u30c3\u30af\u306fPin<Box>\u306b\u5909\u63db\u3055\u308c\u308b<\/h2>\n
\u4e0a\u8a18\u306e\u6df1\u3044\u6df1\u3044\u8a33\u3067\u3059\u304c\u3001\u5b9f\u306f\u3059\u3079\u3066\u306easync\u304c\u4ed8\u304f\u30d6\u30ed\u30c3\u30af\u3068\u95a2\u6570\u306fPin<Box>\u306b\u88cf\u3067\u5909\u63db\u3055\u308c\u3066\u3044\u308b\u306e\u3067\u3059\u3002\u3053\u308c\u307e\u3067\u51fa\u3066\u3053\u306a\u304b\u3063\u305fPin\u3068\u3044\u3046\u65b0\u3057\u3044\u578b\u3082\u767b\u5834\u3057\u307e\u3059…<\/p>\n
\u3053\u308c\u306f\u3001\u975e\u540c\u671f\u51e6\u7406\u306e\u6027\u8cea\u3068\u95a2\u4fc2\u304c\u3042\u308a\u307e\u3059\u3002\u4ee5\u4e0b\u306e\u4f8b\u3067\u8003\u3048\u307e\u3057\u3087\u3046\u3002<\/p>\n
async<\/span> fn<\/span> count_from_file_and_save<\/span>(<\/span>path<\/span>:<\/span> &<\/span>str<\/span>,<\/span> c<\/span>:<\/span> char<\/span>)<\/span> -><\/span> usize<\/span> {<\/span>\r\n    let<\/span> contents<\/span>:<\/span> String<\/span> =<\/span> async_read_to_string<\/span>(<\/span>path<\/span>)<\/span>.await<\/span>;<\/span>\r\n    \/\/ \u3053\u3053\u3067\u6bb5\u968e\u306e\u533a\u5207\u308a\u304c\u5165\u308b<\/span>\r\n    let<\/span> count<\/span>:<\/span> usize<\/span> =<\/span> contents<\/span>.chars<\/span>()<\/span>.filter<\/span>(|<\/span>char<\/span>|<\/span> char<\/span> ==<\/span> c<\/span>)<\/span>.count<\/span>();<\/span>\r\n\r\n    save_count_to_server<\/span>(<\/span>count<\/span>)<\/span>.await<\/span>;<\/span>\r\n    \/\/ \u3053\u3053\u3067\u6bb5\u968e\u306e\u533a\u5207\u308a<\/span>\r\n    count<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u3053\u308c\u306eFuture\u306e\u5b9f\u88c5\u304c\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u306a\u308a\u5f97\u307e\u3059\uff1a<\/p>\n
enum<\/span> CountFromFileAndSave<\/span> {<\/span>\r\n    Read<\/span>,<\/span>\r\n    CountAndSave<\/span>(<\/span>String<\/span>),<\/span>\r\n    Return<\/span>(<\/span>usize<\/span>)<\/span>\r\n}<\/span>\r\n\r\nimpl<\/span> Future<\/span> for<\/span> CountFromFileAndSave<\/span> {<\/span>\r\n    type<\/span> Output<\/span> =<\/span> usize<\/span>;<\/span>\r\n\r\n    fn<\/span> poll<\/span>(<\/span>mut<\/span> self<\/span>:<\/span> Pin<\/span><&<\/span>mut<\/span> Self<\/span>><\/span>,<\/span> cx<\/span>:<\/span> &<\/span>mut<\/span> Context<\/span><<\/span>'_<\/span>><\/span>)<\/span> -><\/span> Poll<\/span><<\/span>Self<\/span>::<\/span>Output<\/span>><\/span> {<\/span>\r\n        loop<\/span> {<\/span>\r\n            match<\/span> self<\/span> {<\/span>\r\n                Read<\/span> =><\/span> {<\/span>\r\n                    \/\/ \u3053\u3053\u3067\u5b9f\u969b\u306b\u30d5\u30a1\u30a4\u30eb\u3092\u8aad\u3080\u51e6\u7406\u3092\u59cb\u3081\u3066\u3001\u305d\u308c\u304c\u7d42\u308f\u308b\u307e\u3067\u3053\u3053\u3092\u901a\u308b\u3002<\/span>\r\n                    \/\/ \u8aad\u3080\u51e6\u7406\u304c\u7d42\u308f\u3063\u3066\u3044\u306a\u3051\u308c\u3070\u3001Waker\u3092\u6e21\u3057\u3066\u3001\u300c\u8d77\u3053\u3055\u308c\u308b\u300d\u307e\u3067\u9032\u307e\u306a\u3044<\/span>\r\n                },<\/span>\r\n                CountAndSave<\/span>(<\/span>contents<\/span>)<\/span> =><\/span> {<\/span>\r\n                    \/\/ \u30b3\u30f3\u30c6\u30f3\u30c4\u3092\u8aad\u3093\u3067\u3001\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u304b\u4f55\u304b\u306b\u305d\u308c\u3092\u4fdd\u5b58\u3059\u308b<\/span>\r\n                },<\/span>\r\n                Return<\/span>(<\/span>count<\/span>)<\/span> =><\/span> {<\/span>\r\n                    \/\/ \u51e6\u7406\u304c\u7d42\u308f\u3063\u305f\u306e\u3067\u3001\u6570\u3092\u8fd4\u3059<\/span>\r\n                }<\/span>\r\n            }<\/span>\r\n        }<\/span>\r\n    }<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u5b9f\u969b\u306b\u3082\u3063\u3068\u6df1\u6398\u308a\u3057\u3066Future\u306e\u5b9f\u88c5\u3092\u6a21\u7bc4\u3057\u3066\u307f\u308b\u3068\u3001\u751f\u6210\u3055\u308c\u308bstruct\u306b\u306f\u3001\u524d\u306e\u6bb5\u968e\u306e\u30b9\u30c6\u30fc\u30c8\u3092\u53c2\u7167\u3059\u308b\u90e8\u5206\u304c\u3042\u3063\u3066\u3001\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304c\u81ea\u8eab\u306e\u5185\u90e8\u306b\u5bfe\u3057\u3066\u30dd\u30a4\u30f3\u30bf\u30fc\u3092\u6301\u3063\u3066\u3044\u308b\u30b3\u30fc\u30c9\u304c\u3042\u308b\u3053\u3068\u306b\u6c17\u3065\u304d\u307e\u3059\u3002<\/p>\n
\u901a\u5e38\u3060\u3068\u3001Rust\u3067struct\u306e\u5185\u90e8\u30dd\u30a4\u30f3\u30bf\u30fc\u3092\u4f5c\u308b\u3053\u3068\u306f\u4e0d\u53ef\u80fd\u3067\u3059\u3002\u306a\u305c\u306a\u3089\u3001\u4ee5\u4e0b\u306e\u4f8b\u3067\u8003\u3048\u308c\u3070\u308f\u304b\u308b\u3088\u3046\u306b\u3001\u305d\u306e\u5185\u90e8\u30dd\u30a4\u30f3\u30bf\u30fc\u304c\u4e0d\u6b63\u306b\u306a\u3089\u306a\u3044\u304b\u4fdd\u8a3c\u3067\u304d\u306a\u3044\u304b\u3089\u3067\u3059\u3002<\/p>\n
struct<\/span> InternalPointer<\/span><<\/span>'a<\/span>><\/span> {<\/span>\r\n    v<\/span>:<\/span> Vec<\/span><<\/span>usize<\/span>><\/span>,<\/span>\r\n    v_ref<\/span>:<\/span> &<\/span>'a<\/span> Vec<\/span><<\/span>usize<\/span>><\/span>,<\/span>\r\n}<\/span>\r\n\r\nlet<\/span> v<\/span> =<\/span> vec!<\/span>[<\/span>0<\/span>,<\/span>1<\/span>,<\/span>2<\/span>],<\/span>\r\nlet<\/span> mut<\/span> int_pointer<\/span> =<\/span> InternalPointer<\/span> {<\/span>\r\n    v_ref<\/span>:<\/span> &<\/span>v<\/span>,<\/span> \/\/ \u4e0d\u53ef\u80fd\u3060\u3051\u3069\u4f8b\u306e\u305f\u3081\u306bOK\u306b\u3057\u3088\u3046<\/span>\r\n    v<\/span>,<\/span>\r\n}<\/span>\r\n\r\nint_pointer<\/span>.v<\/span>.push<\/span>(<\/span>3<\/span>);<\/span> \/\/ \u3053\u308c\u3067Vec\u304c\u30e1\u30e2\u30ea\u4e0a\u3067\u518d\u30a2\u30ed\u30b1\u30fc\u30c8\u3055\u308c\u305f<\/span>\r\nint_pointer<\/span>.v_ref<\/span> \/\/\u3000\u3053\u308c\u306f\u3082\u3046\u3001int_pointer.v\u306b\u7e4b\u304c\u3063\u3066\u304a\u3089\u305a\u3001\u3069\u3053\u304b\u4e0d\u6b63\u306b\u30e1\u30e2\u30ea\u3092\u53c2\u7167\u3057\u3066\u3044\u308b<\/span>\r\n<\/code><\/pre>\n
\u3057\u304b\u3057\u3001\u8a73\u7d30\u306b\u5165\u3089\u305a\u306b\u8aac\u660e\u3059\u308c\u3070\u3001Future\u30c8\u30ec\u30fc\u30c8\u3092\u5b9f\u969b\u306b\u5b9f\u88c5\u3059\u308b\u305f\u3081\u306b\u306f\u3001\u4e0a\u8a18\u306e\u3088\u3046\u306a\u5185\u90e8\u53c2\u7167\u304c\u5fc5\u8981\u4e0d\u53ef\u6b20\u306b\u306a\u308a\u307e\u3059\u306e\u3067\u3001\u56f0\u308a\u307e\u3059\u3002<\/p>\n
\u3053\u3053\u3067Pin\u304c\u767b\u5834\u3059\u308b\u306e\u3067\u3059\u304c\u3001Pin\u306f\u300c\u3053\u306eBox\u306b\u5165\u3063\u3066\u3044\u308b\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306f\u3001\u30e1\u30e2\u30ea\u4e0a\u3067\u52d5\u304b\u306a\u3044\u3068\u7d04\u675f\u3059\u308b\u300d\u3068\u3044\u3046\u4fdd\u8a3c\u3092\u3057\u3066\u304f\u308c\u308b\u3082\u306e\u3067\u3059\u3002<\/p>\n
Future\u306e\u5b9f\u88c5\u3092Pin<Box<**>>\u306b\u5165\u308c\u308c\u3070\u3001\u5185\u90e8\u53c2\u7167\u304c\u3042\u3063\u3066\u3082\u30b3\u30f3\u30d1\u30a4\u30eb\u3067\u304d\u307e\u3059\u3057\u3001\u5b89\u5168\u306b\u5b9f\u884c\u3067\u304d\u307e\u3059\u3002\u306a\u306e\u3067\u3001async fn\u3068async\u30d6\u30ed\u30c3\u30af\u304c\u30b3\u30f3\u30d1\u30a4\u30e9\u30fc\u306b\u3088\u3063\u3066\u79d8\u5bc6\u88cf\u3067\u5b9f\u88c5\u306b\u5c55\u958b\u3055\u308c\u305f\u6642\u306b\u3001Pin<Box>\u306b\u306a\u3063\u3066\u3044\u308b\u306e\u3067\u3059\u3002<\/p>\n
\u3055\u3089\u306b\u3001Send\u3082\u4ed8\u3044\u3066\u304f\u308b\u306e\u306f\u3001\u975e\u540c\u671f\u306e\u30e9\u30f3\u30bf\u30a4\u30e0\u306b\u304a\u3044\u3066\u3001Read\u306e\u6642\u306bFuture::poll\u3092\u547c\u3093\u3067\u51e6\u7406\u3092\u3057\u305f\u30b9\u30ec\u30c3\u30c9\u3068\u3001CountAndSave\u306e\u51e6\u7406\u3092\u3059\u308b\u30b9\u30ec\u30c3\u30c9\u304c\u5fc5\u305a\u3057\u3082\u540c\u3058\u30b9\u30ec\u30c3\u30c9\u3060\u3068\u306f\u9650\u3089\u306a\u3044\u304b\u3089\u3067\u3059\u3002Tokio\u306a\u3069\u306f\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u5411\u4e0a\u306e\u305f\u3081\u306b\u8907\u6570\u306e\u30b9\u30ec\u30c3\u30c9\u3067\u51e6\u7406\u3092\u3057\u3066\u3044\u307e\u3059\u3057\u3001Future\u306e\u5b9f\u88c5\u306f\u5fc5\u305a\u30b9\u30ec\u30c3\u30c9\u30bb\u30fc\u30d5\u3058\u3083\u306a\u3044\u3068\u884c\u3051\u306a\u3044\u3088\u3046\u306b\u306a\u3063\u3066\u3044\u307e\u3059\u3002<\/p>\n
\u6700\u5f8c\u306b’static\u306e\u30e9\u30a4\u30d5\u30bf\u30a4\u30e0\u3082\u4ed8\u304d\u307e\u3059\u304c\u3001\u3053\u308c\u306fFuture\u304c\u6c38\u9060\u306b\u30e1\u30e2\u30ea\u306b\u5c45\u5ea7\u308b\u3068\u3044\u3046\u610f\u5473\u3067\u306f\u306a\u304f\u3001\u3044\u3064\u7d42\u308f\u308b\u304b\u308f\u304b\u3089\u306a\u3044\u304b\u3089\u3001Future\u304c\u5b8c\u4e86\u3059\u308b\u307e\u3067\u30e1\u30e2\u30ea\u306b\u6b8b\u308c\u308b\u3053\u3068\u3092\u4fdd\u8a3c\u3059\u308b\u610f\u5473\u5408\u3044\u306e’static\u3067\u3059\u3002<\/p>\n
\u5b8c\u5168\u306b\u8a73\u7d30\u307e\u3067\u8e0f\u307f\u8fbc\u3093\u3067\u306f\u3044\u306a\u3044\u306e\u3067\u3059\u304c\u3001\u7d50\u8ad6\u3068\u3057\u3066\u3001\u52d5\u7684\u30c7\u30a3\u30b9\u30d1\u30c3\u30c1\u304c\u3067\u304d\u306a\u3044\u3068\u5b9f\u884c\u3067\u304d\u306a\u3044\u306e\u3067\u3059\u3002<\/p>\n
\u30b9\u30c6\u30fc\u30d6\u30ebRust\u3067\u3069\u306e\u3088\u3046\u306b\u3057\u3066async trait\u306e\u4ee3\u308f\u308a\u306b\u306a\u308b\u3082\u306e\u3092\u5b9a\u7fa9\u3067\u304d\u308b\u306e\u304b<\/h1>\n
\u3068\u3082\u304b\u304f\u3001\u4eca\u306eRust\u3067\u306f\u601d\u3046\u3088\u3046\u306b\u30c8\u30ec\u30fc\u30c8\u306b\u975e\u540c\u671f\u30e1\u30bd\u30c3\u30c9\u304c\u304b\u3051\u306a\u3044\u3053\u3068\u304c\u8a33\u3042\u3063\u3066\u3067\u304d\u306a\u3044\u3053\u3068\u3092\u7406\u89e3\u3057\u307e\u3057\u305f\u304c\u3001\u4ee3\u308f\u308a\u306b\u4f55\u304b\u6253\u3064\u624b\u306f\u306a\u3044\u306e\u304b\uff1f<\/p>\n
\u3042\u308a\u307e\u3059\u3002<\/p>\n
\u307e\u305a\u8fd1\u9053\u304b\u3089\u7d39\u4ecb\u3059\u308c\u3070\u3001Rust\u30b3\u30f3\u30d1\u30a4\u30e9\u30fc\u304c\u63a8\u5968\u3057\u3066\u3044\u308b\u3088\u3046\u306b\u3053\u306e\u30af\u30ec\u30fc\u30c8\u3092\u4f7f\u3048\u3070\u3044\u3044\u3067\u3059\u3002<\/p>\n
 <\/p>\n
\u3053\u306e\u30af\u30ec\u30fc\u30c8\u306easync_trait!\u30de\u30af\u30ed\u3092\u4f7f\u3048\u3070\u3067\u304d\u307e\u3059\u3002\u3057\u304b\u3057\u3001\u8a18\u4e8b\u3068\u3057\u3066\u306f\u9762\u767d\u304f\u306a\u3044\u306e\u3067\u3001Pin\u3092\u7406\u89e3\u3057\u305f\u4eca\u3001\u5b9f\u969b\u306basync_trait`\u304c\u3084\u3063\u3066\u3044\u308b\u3053\u3068\u3092\u66f8\u3044\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n
Pin<Box>>\u306e\u623b\u308a\u5024\u3092\u8fd4\u3059\u30c8\u30ec\u30fc\u30c9\u30e1\u30bd\u30c3\u30c9<\/h2>\n
async fn\u304c\u66f8\u3051\u306a\u3048\u3044\u306a\u3089\u3001async fn\u306e\u623b\u308a\u5024\u3092\u8fd4\u305b\u3070\u3044\u3044\u306e\u3067\u3059\uff01<\/p>\n
pub<\/span> trait<\/span> Insertable<\/span>:<\/span> Into<\/span><<\/span>mysql_async<\/span>::<\/span>Params<\/span>><\/span> {<\/span>\r\n    fn<\/span> insert<\/span>(<\/span>self<\/span>)<\/span> -><\/span> Pin<\/span><<\/span>Box<\/span><<\/span>dyn<\/span> Future<\/span><<\/span>Output<\/span> =<\/span> Result<\/span><<\/span>u64<\/span>,<\/span> mysql_async<\/span>::<\/span>Error<\/span>>>>><\/span>;<\/span>\r\n\r\n    fn<\/span> batch<\/span><<\/span>T<\/span>><\/span>(<\/span>values<\/span>:<\/span> T<\/span>)<\/span> -><\/span> Pin<\/span><<\/span>Box<\/span><<\/span>dyn<\/span> Future<\/span><<\/span>Output<\/span> =<\/span> Result<\/span><<\/span>(),<\/span> mysql_async<\/span>::<\/span>Error<\/span>>>>><\/span>\r\n    where<\/span>\r\n        T<\/span>:<\/span> IntoIterator<\/span><<\/span>Item<\/span> =<\/span> Self<\/span>><\/span> +<\/span> Send<\/span> +<\/span> 'static<\/span>,<\/span>\r\n        T<\/span>::<\/span>IntoIter<\/span>:<\/span> Send<\/span>,<\/span>\r\n        Self<\/span>:<\/span> Sized<\/span>;<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u5b9f\u969b\u306b\u4e0a\u8a18\u306e\u3088\u3046\u306a\u30c8\u30ec\u30fc\u30c8\u3092\u5b9f\u88c5\u3059\u308b\u3068\u306a\u308c\u3070\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n
impl<\/span> Insertable<\/span> for<\/span> WpPost<\/span> {<\/span>\r\n    fn<\/span> insert<\/span>(<\/span>\r\n        self<\/span>,<\/span>\r\n    )<\/span> -><\/span> std<\/span>::<\/span>pin<\/span>::<\/span>Pin<\/span><<\/span>Box<\/span><<\/span>dyn<\/span> std<\/span>::<\/span>future<\/span>::<\/span>Future<\/span><<\/span>Output<\/span> =<\/span> Result<\/span><<\/span>u64<\/span>,<\/span> mysql_async<\/span>::<\/span>Error<\/span>>>>><\/span> {<\/span>\r\n        let<\/span> fut<\/span> =<\/span> async<\/span> {<\/span>\r\n            let<\/span> mut<\/span> conn<\/span> =<\/span> get_conn<\/span>()<\/span>.await<\/span>?<\/span>;<\/span>\r\n\r\n            let<\/span> stmt<\/span> =<\/span> Self<\/span>::<\/span>get_stmt<\/span>(<\/span>&<\/span>mut<\/span> conn<\/span>)<\/span>.await<\/span>?<\/span>;<\/span>\r\n\r\n            conn<\/span>.exec_drop<\/span>(<\/span>stmt<\/span>,<\/span> self<\/span>)<\/span>.await<\/span>?<\/span>;<\/span>\r\n\r\n            let<\/span> post_id<\/span>:<\/span> u64<\/span> =<\/span> conn<\/span>\r\n                .exec_first<\/span>(<\/span>\"SELECT LAST_INSERT_ID();\"<\/span>,<\/span> ())<\/span>\r\n                .await<\/span>?<\/span>\r\n                .unwrap<\/span>();<\/span>\r\n\r\n            Ok<\/span>(<\/span>post_id<\/span>)<\/span>\r\n        };<\/span>\r\n\r\n        Box<\/span>::<\/span>pin<\/span>(<\/span>fut<\/span>)<\/span>\r\n    }<\/span>\r\n    ...<\/span>\r\n}<\/span>\r\n<\/code><\/pre>\n
\u3055\u3089\u306bmacro_rules!\u3092\u4f7f\u3063\u3066async_traits\u306e\u30af\u30ec\u30fc\u30c8\u304c\u3084\u308b\u3088\u3046\u306b\u81ea\u52d5\u7684\u306basync fn\u3092fn foo() { Box::pin(async {…}) }\u306b\u66f8\u304d\u63db\u3048\u308b\u3088\u3046\u306b\u3082\u3067\u304d\u307e\u3059\u3002<\/p>\n
\u307e\u3068\u3081<\/h1>\n
\u9577\u3044\u8a18\u4e8b\u306b\u306a\u3063\u3066\u3057\u307e\u3044\u307e\u3057\u305f\u304c\u3001\u975e\u540c\u671f\u306e\u30c8\u30ec\u30fc\u30c8\u30e1\u30bd\u30c3\u30c9\u304cRust\u6a19\u6e96\u30e9\u30a4\u30d6\u30e9\u30ea\u306b\u5165\u3089\u306a\u3044\u7406\u7531\u3068\u3001\u4ee3\u308f\u308a\u306b\u3069\u3046\u3084\u3063\u3066\u975e\u540c\u671f\u30e1\u30bd\u30c3\u30c9\u3092\u30c8\u30ec\u30fc\u30c8\u5185\u3067\u66f8\u3051\u308b\u304b\u306b\u3064\u3044\u3066\u63d0\u6848\u3057\u307e\u3057\u305f\u3002<\/p>\n
\u672c\u8a18\u4e8b\u3067\u306fRust\u306e\u30b3\u30f3\u30d1\u30a4\u30e9\u30fc\u304c\u88cf\u3067\u5c55\u958b\u3057\u3066\u304f\u308c\u308bFuture\u306e\u5b9f\u88c5\u306b\u3064\u3044\u3066\u306f\u5927\u5e45\u306b\u7701\u7565\u3057\u305f\u306e\u304c\u591a\u5c11\u6094\u3057\u3044\u306e\u3067\u3059\u304c\u3001\u8208\u5473\u3092\u304a\u6301\u3061\u306e\u65b9\u306f\u3001\u305c\u3072rust\u306easync state machine\u306b\u3064\u3044\u3066\u8abf\u3079\u3066\u3044\u305f\u3060\u3051\u308c\u3070\u3068\u601d\u3044\u307e\u3059\u3002\u82f1\u8a9e\u3067\u3082OK\u306a\u65b9\u306f\u3001\u305c\u3072Jon Gjengset\u3055\u3093\u306eRust\u306e\u975e\u540c\u671f\u51e6\u7406\u306b\u3064\u3044\u3066\u306e\u8b1b\u7fa9\u3092\u805e\u3044\u305f\u3089\u3044\u3044\u3068\u601d\u3044\u307e\u3059\u3002Pin\u3001State Machine\u306a\u3069\u3001\u5185\u90e8\u7684\u306a\u8a71\u3092\u3088\u308a\u7d30\u304b\u304f\u6df1\u6398\u308a\u3057\u3066\u304f\u308c\u307e\u3059\u3002<\/p>\n
 <\/p>\n
\u305d\u308c\u3067\u306f\u975e\u540c\u671f\u51e6\u7406\u3092\u7b46\u8005\u3068\u540c\u69d8\u306b\u697d\u3057\u304f\u66f8\u3051\u3066\u3044\u308b\u3053\u3068\u3092\u304a\u7948\u308a\u3057\u307e\u3059\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"
\u6982\u8981 Rust\u3067\u30c8\u30ec\u30fc\u30c8\u30e1\u30bd\u30c3\u30c9\u306basync\u304c\u4f7f\u3048\u306a\u3044\u304c\u3001\u4f7f\u3048\u306a\u3044\u7406\u7531\u3068\u3001\u4ee3\u308f\u308a\u306b\u3067\u304d\u308b\u3053\u3068\u3092\u89e3\u8aac\u3057\u307e\u3059\u3002 a […]<\/p>\n","protected":false},"author":6,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-45273","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"yoast_head":"\n- Blog - Silicon Cloud<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.silicloud.com\/zh\/blog\/45273-2\/\" \/>\n<meta property=\"og:locale\" content=\"zh_CN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:description\" content=\"\u6982\u8981 Rust\u3067\u30c8\u30ec\u30fc\u30c8\u30e1\u30bd\u30c3\u30c9\u306basync\u304c\u4f7f\u3048\u306a\u3044\u304c\u3001\u4f7f\u3048\u306a\u3044\u7406\u7531\u3068\u3001\u4ee3\u308f\u308a\u306b\u3067\u304d\u308b\u3053\u3068\u3092\u89e3\u8aac\u3057\u307e\u3059\u3002 a […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.silicloud.com\/zh\/blog\/45273-2\/\" \/>\n<meta property=\"og:site_name\" content=\"Blog - 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