错误FS3039:不允许直接引用生成的类型"MyType"

Question

以下类型提供程序旨在创建GeneratedNamespace.MyType接受类型的静态参数string并仅包含空构造函数

namespace TypeProviderTest

open Microsoft.FSharp.Core.CompilerServices
open ProviderImplementation.ProvidedTypes
open System.Reflection
open System

[<TypeProvider>]
type MyTypeProvider(config:TypeProviderConfig) as this = 
    inherit TypeProviderForNamespaces()
    let namespaceName="GeneratedNamespace"
    let assembly = Assembly.LoadFrom(config.RuntimeAssembly)

    //Provides definition, based on type parameters
    let instantiationFunction typeName (typeParams:obj[]) =
        match typeParams with
                | [|:? string as param|] -> 
                    //Creates an empty non-erased type
                    let definition = ProvidedTypeDefinition(
                                        assembly,
                                        namespaceName,
                                        typeName,
                                        Some typedefof<Object>,
                                        IsErased = false
                                        )

                    //Creates an empty constructor
                    let emptyCtor = ProvidedConstructor (parameters = [])
                    //Provides a call to base constructor 
                    //(https://stackoverflow.com/questions/22520352/)
                    //Doesn't seem to help
                    let objCtor = typedefof<Object>.GetType().GetConstructor([||])
                    emptyCtor.BaseConstructorCall <- (fun _ -> objCtor,[])
                    emptyCtor.AddXmlDoc("Empty constructor test")

                    definition.AddMember(emptyCtor)
                    definition
                | _ -> failwith "That was not supported"

    let  staticParams = [ProvidedStaticParameter("value",typedefof<string>)] 
    let t = ProvidedTypeDefinition(assembly,namespaceName,"MyType",Some typedefof<Object>)
    do t.DefineStaticParameters(staticParams,instantiationFunction)


    do this.AddNamespace(namespaceName,[t])
[<assembly:TypeProviderAssembly>]
do ()

当我尝试像这样使用它

open System
open GeneratedNamespace
type X = MyType<"Abacaba">
[<EntryPoint>]
let main argv = 
    printfn "%A %A" typedefof<X> (new X())
    Console.ReadLine() |> ignore
    0 

该行type X = MyType<"Abacaba">产生错误

错误FS3039:不允许直接引用生成的类型"MyType".

我添加了一个基础构造函数调用,但它没有帮助

类型提供者是有意生成的

我的类型提供程序中是否有错误？

Answer 1

我不确定如何使它完全正常工作,但我认为你得到错误的原因是参数化类型是一个擦除类型(虽然提供静态参数时返回的类型不是擦除类型).

添加IsErased = false到t使错误消失:

let  staticParams = [ProvidedStaticParameter("value",typedefof<string>)] 
let t = 
  ProvidedTypeDefinition
    (assembly,namespaceName,"MyType",Some typedefof<Object>,IsErased = false)
do t.DefineStaticParameters(staticParams,instantiationFunction)

有了这个,代码可以编译,但尝试创建一个实例使用new X()给出:

错误FS0192:内部错误:null:GetTRefType

所以,我可能还缺少其他一些东西.也许它可以指出你正确的方向!