问题与通用操作字典

作者: 無口君哦哦
发布时间: 2024-12-09 04:54:17 (1月前)
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绵绵 | 2019-08-31 10-32

<div class =“post-text”itemprop =“text”> <P> 这种行为似乎是一种不规则或错误。我也期待这对所有操作来说都是一样的。 </p> <P> 无论如何，您可以通过捕获来解决此问题 <code> ops </code> 在静态内联成员中（而不是在类型上使用静态解析的类型参数）。以下工作对我来说很好： </p> <pre> <code> type CalculatorAgent<'T>(ops:INumerics<'T>) = let agent = Agent<CalculatorMsg<'T>>.Start(fun inbox -> let rec loop () = async { let! msg = inbox.TryReceive() match msg with | Some(Add (x, y, rep)) -> printfn "Adding %A and %A ..." x y let res = ops.Add(x, y) res |> rep.Reply return! loop() | Some(Sub (x, y, rep)) -> printfn "Subtracting %A from %A ..." y x let res = ops.Sub(x, y) res |> rep.Reply return! loop() | Some(Mul (x, y, rep)) -> printfn "Multiplying %A by %A ... " y x let res = ops.Mul(x, y) res |> rep.Reply return! loop() | Some(Div (x, y, rep)) -> printfn "Dividing %A by %A ..." x y if ops.Neq(y, ops.Zer) then let res = ops.Div(x, y) res |> rep.Reply else printfn "#DIV/0" return! loop() | _ -> return! loop() } loop() ) // timeout = infinit => t = -1 let t = 1000 member this.Add(x, y) = agent.PostAndTryAsyncReply((fun rep -> Add (x, y, rep)), t) |> Async.RunSynchronously member this.Subtract(x, y) = agent.PostAndTryAsyncReply((fun rep -> Sub (x, y, rep)), t) |> Async.RunSynchronously member this.Multiply(x, y) = agent.PostAndTryAsyncReply((fun rep -> Mul (x, y, rep)), t) |> Async.RunSynchronously member this.Divide(x, y) = agent.PostAndTryAsyncReply((fun rep -> Div (x, y, rep)), t) |> Async.RunSynchronously type CalculatorAgent = static member inline Create() = let ops = { new INumerics<_> with member ops.Zer = LanguagePrimitives.GenericZero<_> member ops.Add(x, y) = x + y member ops.Sub(x, y) = x - y member ops.Mul(x, y) = x * y member ops.Div(x, y) = x / y member ops.Neq(x, y) = x <> y } CalculatorAgent<_>(ops) let calculatorAgentI = CalculatorAgent.Create<int>() (2, 1) |> calculatorAgentI.Add (2, 1) |> calculatorAgentI.Subtract (2, 1) |> calculatorAgentI.Multiply (2, 1) |> calculatorAgentI.Divide (2, 0) |> calculatorAgentI.Divide </code> </pre> <P> 也就是说，我认为你真正需要通用数字代码的情况非常罕见 - 所以我怀疑最好避免完全引入所有这些复杂性，只需编写特定数字类型的代码。 </p> </DIV>

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1#
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樱花弄๑•ั็•็ | 2019-08-31 10-32

<div class =“post-text”itemprop =“text”> <P> 在附加调试器的情况下运行此代码，您将看到在尝试运行时遇到System.NotSupportedException <code> sub </code> 代理内部的功能： </p> <pre> <code> System.NotSupportedException occurred HResult=0x80131515 Message=Specified method is not supported. Source=FSI-ASSEMBLY StackTrace: at FSI_0002.ops@60.FSI_0002-INumerics`1-Sub(T X1, T X2) </code> </pre> <P> 你得到的原因 <code> val it : int option = None </code> 是因为你指定了1秒的超时，并且在抛出异常之后你正在尝试。 </p> <P> 打电话给 <code> sub </code> 函数直接工作正常，但通过调用它 <code> CalculatorAgent </code> 上课没有。这是因为在这种情况下类型参数是在类上定义的，并且在F＃中对类的结构类型约束的使用存在限制。我建议你继续阅读 <a href="https://docs.microsoft.com/en-us/dotnet/fsharp/language-reference/generics/statically-resolved-type-parameters" rel="nofollow noreferrer"> 静态分辨的类型参数 </A> 和他们的局限。 </p> </DIV>

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