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爲了學習F#和.Net,我一直在玩即將發佈的DLR。爲了實現這個目標,我一直在反思,努力實現一個與clr很好地集成的基本類型系統。雖然我能夠實例化一個擴展Object的簡單類型,但在調用它定義的方法時出現錯誤。使用委託/ DLR Lambdas覆蓋實例方法?
因爲在一天結束時DLR LambdaExpressions會編譯到委託中,我所做的是將生成的MethodInfo從生成的委託中取出並調用它,並使用生成的方法的參數填充堆棧。然後返回它。這是我的錯誤。
這裏是我的代碼:
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)|])
這是我的錯誤,從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
任何幫助或建議,將不勝感激 - 我有點淨福利局的,所以我的錯可能很簡單。
Mike Kohout
在黑暗中拍攝 - 在使用fsc.exe編譯時是否獲得相同的行爲? MethodAccessException表明可能有些東西不是公開的,但你所有的代碼似乎都會產生公共方法,所以我不知道爲什麼會發生這種情況...... – Brian 2009-05-20 15:28:44