使用Reflection.Emit创建具有属性的接口

Question

I need to generate an interface. I'va a problem to generate (emit) the virtual properties. It seems they are not generated.

I figure out I'm doing something wrong:

private static TypeBuilder getTypeBuilder()
    {
        var typeSignature = "DynamicDigitalInput";
        var an = new AssemblyName(typeSignature);

        AssemblyBuilder assemblyBuilder = AppDomain.CurrentDomain.DefineDynamicAssembly(an, AssemblyBuilderAccess.Run);
        ModuleBuilder moduleBuilder = assemblyBuilder.DefineDynamicModule("DynamicDomain");
        TypeBuilder tb = moduleBuilder.DefineType(typeSignature
                            , TypeAttributes.Public |
                            TypeAttributes.Interface |
                            TypeAttributes.Abstract |
                            TypeAttributes.AutoClass |
                            TypeAttributes.AnsiClass |
                            TypeAttributes.BeforeFieldInit |
                            TypeAttributes.AutoLayout
                            , null);

        return tb;
    }

    private static void createProperty(TypeBuilder tb, string propertyName, Type propertyType)
    {

        PropertyBuilder propertyBuilder = tb.DefineProperty(propertyName, PropertyAttributes.HasDefault, propertyType, null);
    }

In order to generate the interface:

TypeBuilder tb = getTypeBuilder();
createProperty(tb, "p1", String.GetType());
createProperty(tb, "p2", Int32.GetType());

When I perform this:

Type i = tb.CreateType();
System.Reflection.PropertyInfo p1 = type.GetProperty("p1");

p1 is null .

What am I doing wrong?

Answer 1

The property is not defined correctly. In order for GetProperty to work, the property must have at least one public getter or setter. Right now, is does not have even one getter or setter, so they never can be public.

So, you have to create a public get-method and/or a public set-method (using the MethodBuilder). Try this:

private static void createProperty(TypeBuilder tb, string propertyName, Type propertyType)
{
    PropertyBuilder propertyBuilder = tb.DefineProperty(propertyName, PropertyAttributes.HasDefault, propertyType, null);
    MethodBuilder methodBuilder = tb.DefineMethod("get_" + propertyName, MethodAttributes.Virtual | MethodAttributes.Abstract | MethodAttributes.Public);
    propertyBuilder.SetGetMethod(methodBuilder);
}