F# 使用委托/DLR Lambdas重写实例方法？

为了学习F和.Net，我一直在玩即将发布的DLR

为此，我一直在研究反射，努力实现一个与clr很好集成的基本类型系统。虽然我能够实例化一个扩展对象的简单类型，但调用它定义的方法时会出错

因为在一天结束时，DLR LambdaExpressions向下编译为委托，我要做的是从生成的委托中取出生成的MethodInfo并调用它，用生成的方法的参数填充堆栈。然后把它还给我。在这一点上，我得到了我的错误

这是我的密码：

open System
open System.Reflection
open System.Reflection.Emit

type ConstructorInformation=
    {Types:System.Type array}

type MethodInformation=
    {ParamTypes:System.Type array;
     Name:string
     Impl:System.Delegate}


let rec addConstructors (t:TypeBuilder) (baseType:System.Type) constructorInfos =
    match constructorInfos with
        |ci::rest ->
            let cb = t.DefineConstructor(MethodAttributes.Public, CallingConventions.Standard,ci.Types)
            let ilGen = cb.GetILGenerator()

            ilGen.Emit(OpCodes.Ldarg_0)
            Array.iteri (fun (index:int) _-> ilGen.Emit(OpCodes.Ldarg, index+1)) ci.Types
            ilGen.Emit( OpCodes.Call, baseType.GetConstructor(ci.Types) )
            addConstructors t baseType rest
        |[] -> ()

let rec addMethods (tb:TypeBuilder) baseType methodInfos =
    match methodInfos with
    |mi::rest ->
        let mb = tb.DefineMethod(mi.Name, MethodAttributes.Public, typeof<obj>, mi.ParamTypes)
        let ilGen = mb.GetILGenerator()
        ilGen.Emit(OpCodes.Ldarg_0)
        Array.iteri (fun index _ -> ilGen.Emit(OpCodes.Ldarg, index+1)) mi.ParamTypes
        ilGen.EmitCall(OpCodes.Call, mi.Impl.Method, mi.ParamTypes)
        ilGen.Emit(OpCodes.Ret)
        addMethods tb baseType rest
    |[] -> ()

let defineType (baseType:System.Type) constructorInfos methodInfos= 
    let ab =  AppDomain.CurrentDomain.DefineDynamicAssembly( AssemblyName("test"), AssemblyBuilderAccess.Run)
    let mb = ab.DefineDynamicModule("test")
    let typeBuilder = mb.DefineType("testType", TypeAttributes.Public, baseType)// | TypeAttributes.Class
    addConstructors typeBuilder baseType constructorInfos
    addMethods typeBuilder baseType methodInfos
    typeBuilder.CreateType()

type Delegate1 = delegate of obj -> obj
let echo y:#obj= (y :> obj)
let del1 : Delegate1 = new Delegate1(echo)

let mis:MethodInformation list=[{Impl=del1; Name="Echo"; ParamTypes=[|(typeof<obj>)|]}]
let cis:ConstructorInformation list=[]
let t= defineType (typeof<obj>) cis mis
let cinfo = t.GetConstructor([||])
let instance =cinfo.Invoke([||])
instance.GetType()
(t.GetMethod("Echo")).Invoke(instance, [| (1:>obj)|])

以下是我的错误，来自fsi：

System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.MethodAccessException: clo@51.Invoke(System.Object)
   at testType.Echo(Object )
   --- End of inner exception stack trace ---
   at System.RuntimeMethodHandle._InvokeMethodFast(Object target, Object[] arguments, SignatureStruct& sig, MethodAttributes methodAttributes, RuntimeTypeHandle typeOwner)
   at System.RuntimeMethodHandle.InvokeMethodFast(Object target, Object[] arguments, Signature sig, MethodAttributes methodAttributes, RuntimeTypeHandle typeOwner)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks)
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
   at <StartupCode$FSI_0002>.$FSI_0002._main()
stopped due to error

任何帮助或建议都将不胜感激——我是一个.Net新手，所以我的错误可能很简单

---

迈克·科霍特

好吧，我解决了。生成的cil不正确。此外，我还必须对委托进行dynamicinvoke，而不是它所面对的函数

#light

open System
open System.Reflection
open System.Reflection.Emit

type ConstructorInformation=
    {Types:System.Type array}

type MethodInformation=
    {ParamTypes:System.Type array;
     Name:string;
     Impl:System.Delegate;
     mutable Field:FieldBuilder option}


let rec addConstructors (t:TypeBuilder) (baseType:System.Type) constructorInfos =
    match constructorInfos with
        |ci::rest ->
            let cb = t.DefineConstructor(MethodAttributes.Public, CallingConventions.Standard,ci.Types)
            let ilGen = cb.GetILGenerator()

            ilGen.Emit(OpCodes.Ldarg_0)
            Array.iteri (fun (index:int) _-> ilGen.Emit(OpCodes.Ldarg, index+1)) ci.Types
            ilGen.Emit( OpCodes.Call, baseType.GetConstructor(ci.Types) )
            addConstructors t baseType rest
        |[] -> ()

let rec addMethods (tb:TypeBuilder) baseType methodInfos =
    match methodInfos with
    |mi::rest ->
        let fb = tb.DefineField(mi.Name+"_field", typeof<Delegate>, FieldAttributes.Public);
        mi.Field <- Some(fb)
        let mb = tb.DefineMethod(mi.Name, MethodAttributes.Public, typeof<obj>, mi.ParamTypes)
        let ilGen = mb.GetILGenerator()
        let arrayLocal = ilGen.DeclareLocal((typeof<obj[]>))
        ilGen.Emit(OpCodes.Ldarg_0)
        ilGen.Emit(OpCodes.Ldfld, fb)
        ilGen.Emit(OpCodes.Ldc_I4, Array.length mi.ParamTypes)
        ilGen.Emit(OpCodes.Newarr, typeof<obj>)
        ilGen.Emit(OpCodes.Stloc, arrayLocal)
        ilGen.Emit(OpCodes.Ldloc, arrayLocal)
        Array.iteri (fun index _ -> ilGen.Emit(OpCodes.Ldc_I4, index)
                                    ilGen.Emit(OpCodes.Ldarg, index+1)
                                    ilGen.Emit(OpCodes.Stelem_Ref)
                                    ilGen.Emit(OpCodes.Ldloc, arrayLocal)) mi.ParamTypes
        ilGen.EmitCall(OpCodes.Callvirt, (mi.Impl.GetType()).GetMethod("DynamicInvoke", [|(typeof<obj[]>)|]), mi.ParamTypes)
        ilGen.Emit(OpCodes.Ret)
        addMethods tb baseType rest
    |[] -> ()

let defineType (baseType:System.Type) constructorInfos methodInfos= 
    let ab =  AppDomain.CurrentDomain.DefineDynamicAssembly( AssemblyName("test"), AssemblyBuilderAccess.Run)
    let mb = ab.DefineDynamicModule("test")
    let typeBuilder = mb.DefineType("testType", TypeAttributes.Public, baseType)// | TypeAttributes.Class
    addConstructors typeBuilder baseType constructorInfos
    addMethods typeBuilder baseType methodInfos
    typeBuilder.CreateType()

type Delegate1 = delegate of obj -> obj
let echo y:#obj= (y :> obj)
let del1 : Delegate1 = new Delegate1(echo)

type Delegate2 = delegate of obj * obj -> obj
let echoFirst (x:#obj) (y:#obj)=(x:>obj)
let echoFirstDelegate:Delegate2 = new Delegate2(echoFirst)
echoFirstDelegate.DynamicInvoke( [|(1:>obj);(2:>obj)|])
//let mis:MethodInformation list=[{Impl=del1; Name="Echo"; ParamTypes=[|(typeof<obj>)|];Field=None}]
//let cis:ConstructorInformation list=[]
//let t= defineType (typeof<obj>) cis mis
//let cinfo = t.GetConstructor([||])
//let instance =cinfo.Invoke([||])
//instance.GetType()
//(t.GetField("Echo_field")).SetValue(instance, del1)
//let fieldDelegate = (t.GetField("Echo_field")).GetValue(instance) :?> Delegate
//(t.GetMethod("Echo")).Invoke(instance, [| (1:>obj)|])

//del1.DynamicInvoke( [|(1:>obj)|])

let mis:MethodInformation list=[{Impl=del1; Name="Echo"; ParamTypes=[|(typeof<obj>)|];Field=None};
                                {Impl=echoFirstDelegate; Name="EchoFirst"; ParamTypes=[| (typeof<obj>);(typeof<obj>)|]; Field=None}]
let cis:ConstructorInformation list=[]
let t= defineType (typeof<obj>) cis mis
let cinfo = t.GetConstructor([||])
let instance =cinfo.Invoke([||])
instance.GetType()
(t.GetField("Echo_field")).SetValue(instance, del1)
let fieldDelegate = (t.GetField("Echo_field")).GetValue(instance) :?> Delegate
(t.GetMethod("Echo")).Invoke(instance, [| (1:>obj)|])
(t.GetField("EchoFirst_field")).SetValue(instance, echoFirstDelegate)
(t.GetMethod("EchoFirst")).Invoke(instance, [| (1:>obj);(2:>obj)|])

---

暗中拍摄-在使用fsc.exe编译时，您是否会获得相同的行为？MethodAccessException表明可能有些东西不是公共的，但您的所有代码似乎都生成了公共方法，所以我不确定为什么会发生这种情况……感谢您的建议，Brian，但看起来它仍然在发生。使用fsc/vs2008编译后，我将通过vs2008的调试异常详细信息窗格获取此消息：System.Reflection.TargetInvocationException未经处理消息：异常已由调用的目标引发。我相信问题在于委托对象本身不在堆栈上……需要一些时间来验证，但我认为这可能是我的问题。根据委托的Method属性，它指向的方法是实例方法。这意味着委托对象本身必须在堆栈上。。。。我从委托的MethodInfo中思考：IsSpecialName=false；IsStatic=假；IsVirtual=false；我现在和这个问题开始时一样不知所措。我尝试了我在上一个问题中提到的方法。我尝试使用newarr操作码将所有arg绑定到一个数组中，然后调用该方法。