VB.NET里面不允许GetType(System.Void)

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VB.NET里面不允许GetType(System.Void)

Dim CompTypeArray1() As Type = New Type() {GetType(System.Void)}

error: 不支持Void类型。

Type[] CompTypeArray1 = new Type[] {

typeof(void)};

而在C#里，允许 typoof(void)

MSDN中的解释是：这个结构体使用System.Reflection的命名空间，不具有成员，不能做成Instance(实体)。

解决方法是：
VB.NET： type = Nothing 而不能是GetType(Void) 或 GetType(System.Void)
C# : type = typeof(void);

原因:VB.NET中没有返回值的方法，由关键字Sub定义成了Sub ,而不是Void类型的Function ,VB.NET中，不需要Void这个关键字，即也就是Nothing 类型的时候，就会被解释成没有返回值的Sub.

MethodBuilder myMethod1 = helloWorldClass.DefineMethod("OnClick",

MethodAttributes.Public, null, new Type[]{typeof(Object)});

ILGenerator methodIL1 = myMethod1.GetILGenerator();

methodIL1.Emit(OpCodes.Ret);

MethodBuilder myMethod2 = helloWorldClass.DefineMethod("OnMouseUp",

MethodAttributes.Public, typeof(void), new Type[]{typeof(Object)});

ILGenerator methodIL2 = myMethod2.GetILGenerator();

methodIL2.Emit(OpCodes.Ret);

if(myMethod1.ReturnType ==myMethod2.ReturnType)

{

Console.WriteLine("met1.ret = met2.ret");

}

以上的这段代码说明，C#中，返回值的类型（DefineMethod的第三引数）处的null 和typeof(void)的意义是不一样的。null的时候，returntype是未定义的状态，typeof(void )才是C#中希望的void类型。

VB.NET中只用Nothing 而不能用GetType(Void).

提供测试全部代码，其实来自MSDN

using System;

using System.Threading;

using System.Reflection;

using System.Reflection.Emit;

public class MyApplication

{

public delegate void MyEvent(Object temp);

public static void MyMain()

{

TypeBuilder helloWorldClass = CreateCallee(Thread.GetDomain());

EventInfo[] info =

helloWorldClass.GetEvents(BindingFlags.Public | BindingFlags.Instance);

Console.WriteLine("'HelloWorld' type has following events :");

for(int i=0; i < info.Length; i++)

{

Console.WriteLine(info[i].Name);

}

// Create the callee transient dynamic assembly.

private static TypeBuilder CreateCallee(AppDomain myDomain)

{

AssemblyName assemblyName = new AssemblyName();

assemblyName.Name = "EmittedAssembly";

// Create the callee dynamic assembly.

AssemblyBuilder myAssembly =

myDomain.DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Run);

// Create a dynamic module named "CalleeModule" in the callee.

ModuleBuilder myModule = myAssembly.DefineDynamicModule("EmittedModule");

// Define a public class named "HelloWorld" in the assembly.

TypeBuilder helloWorldClass =

myModule.DefineType("HelloWorld", TypeAttributes.Public);

MethodBuilder myMethod1 = helloWorldClass.DefineMethod("OnClick",

MethodAttributes.Public, null, new Type[]{typeof(Object)});

ILGenerator methodIL1 = myMethod1.GetILGenerator();

methodIL1.Emit(OpCodes.Ret);

MethodBuilder myMethod2 = helloWorldClass.DefineMethod("OnMouseUp",

MethodAttributes.Public, typeof(void), new Type[]{typeof(Object)});

ILGenerator methodIL2 = myMethod2.GetILGenerator();

methodIL2.Emit(OpCodes.Ret);

if(myMethod1.ReturnType ==myMethod2.ReturnType)

{

Console.WriteLine("met1.ret = met2.ret");

}

// Create the events.

EventBuilder myEvent1 = helloWorldClass.DefineEvent("Click", EventAttributes.None,

typeof(MyEvent));

myEvent1.SetRaiseMethod(myMethod1);

EventBuilder myEvent2 = helloWorldClass.DefineEvent("MouseUp", EventAttributes.None,

typeof(MyEvent));

myEvent2.SetRaiseMethod(myMethod2);

helloWorldClass.CreateType();

return(helloWorldClass);

}

出处：https://www.cnblogs.com/Bluse/archive/2005/10/17/256645.html

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