使用委托/ DLR Lambdas覆盖实例方法？

Question

为了学习F＃和.Net，我一直在玩即将发布的DLR。为了实现这个目标，我一直在反思，努力实现一个与clr很好地集成的基本类型系统。虽然我能够实例化一个扩展Object的简单类型，但在调用它定义的方法时出现错误。

因为在一天结束时DLR LambdaExpressions会编译到委托中，我所做的是将生成的MethodInfo从生成的委托中取出并调用它，并使用生成的方法的参数填充堆栈。然后返回它。这是我的错误。

这里是我的代码：

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)|]) 

这是我的错误，从FSI：

System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.MethodAccessException: [email protected](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，将不胜感激 - 我有点净福利局的，所以我的错可能很简单。

Mike Kohout

Answer 1

嗯，我解决了它。生成的cil很糟糕。另外，我不得不对代表进行动态调用，而不是它所面对的功能。

#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)|])