使用Reflection.Emit覆盖属性定义

Question

我正在尝试使用Reflection.Emit(TypeBuilder)实现此模式:

public class ClassToBeProxied
{
    public virtual object Property1 { get; set; }
}

public class Proxy : ClassToBeProxied
{
    [AttributeToBeAdded]
    public override object Property1
    {
        get
        {
            //do something else to return the object - i.e get it from the database
            return null; //stub
        }
        set
        {
            //do something else to set the object - i.e, save it to a database
        }
    }        
}

如果我所做的只是拦截get和set方法,那么这有效:

PropertyInfo info = typeof(ClassToBeProxied).GetProperty("Property1", BindingFlags.Public | BindingFlags.Instance);
{
    MethodBuilder pGet = typeBuilder.DefineMethod("get_" + info.Name, MethodAttributes.Virtual | MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.HideBySig, info.PropertyType, Type.EmptyTypes);
    ILGenerator pILGet = pGet.GetILGenerator();

    //The proxy object
    pILGet.Emit(OpCodes.Ldarg_0);
    //The database
    pILGet.Emit(OpCodes.Ldfld, database);
    //The proxy object
    pILGet.Emit(OpCodes.Ldarg_0);
    //The ObjectId to look for
    pILGet.Emit(OpCodes.Ldfld, f);
    pILGet.Emit(OpCodes.Callvirt, typeof(MongoDatabase).GetMethod("Find", BindingFlags.Public | BindingFlags.Instance, null, new Type[] { typeof(ObjectId) }, null).MakeGenericMethod(info.PropertyType));
    pILGet.Emit(OpCodes.Ret);

    MethodBuilder pSet = typeBuilder.DefineMethod("set_" + info.Name, MethodAttributes.Virtual | MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.HideBySig, null, new Type[] { info.PropertyType });
    ILGenerator pILSet = pSet.GetILGenerator();
    pILSet.Emit(OpCodes.Ldarg_0);
    pILSet.Emit(OpCodes.Ldarg_1);
    pILSet.Emit(OpCodes.Ldarg_0);
    pILSet.Emit(OpCodes.Ldfld, database);
    pILSet.Emit(OpCodes.Call, typeof(ProxyBuilder).GetMethod("SetValueHelper", BindingFlags.Public | BindingFlags.Static, null, new Type[] { typeof(object), typeof(MongoDatabase) }, null));
    pILSet.Emit(OpCodes.Stfld, f);
    pILSet.Emit(OpCodes.Ret);

    //Edit:  Added fix
    newProp.SetSetMethod(pSet);
    newProp.SetGetMethod(pGet);
}

但我需要做的是为属性添加一个属性.我无法弄清楚如何做到这一点.

如果我添加一个新的PropertyDefinition:

PropertyBuilder newProp = typeBuilder.DefineProperty(info.Name, PropertyAttributes.None, info.PropertyType, Type.EmptyTypes);
newProp.SetCustomAttribute(new CustomAttributeBuilder(typeof(AttributeToBeAdded).GetConstructor(Type.EmptyTypes), Type.EmptyTypes, new FieldInfo[0], new object[0]));

然后在生成的类型上调用GetProperties(),出现两个具有相同名称的属性.但是,如果我手动构建代码(如上例所示),并调用typeof(Proxy).GetProperties(),则只能看到一个Property(派生类属性).这是我需要的行为,但我似乎无法用Reflection.Emit到达那里

如果我需要添加更多信息以使问题更清楚,请告诉我.

Answer 1

所以答案是添加这个：

newProp.SetSetMethod(pSet);
newProp.SetGetMethod(pGet);

请参阅编辑后的问题。

答案有点矛盾http://www.gutgames.com/post/Overridding-a-Property-With-ReflectionEmit/

但这似乎有效。