在运行时将OnpropertyChanged添加到属性setter

时间:2016-11-27 14:20:58

标签: c# reflection cil

我在运行时使用反射创建类,基于ClassName和属性列表,它们是父类" DataObject"的子类,它实现了INotifyPropertyChanged和OnPropertyChanged,但是当我尝试通过以下方法设置属性时,我得到一个" Field令牌超出范围"例外:

        private void dataGrid_AddingNewItem(object sender, AddingNewItemEventArgs e)
    {
        object obj = Activator.CreateInstance(currentType);

        PropertyInfo[] properties = obj.GetType().GetProperties();
        try
        {
            foreach (PropertyInfo prop in properties)
            {
                if (prop.PropertyType == typeof(string) && prop.CanWrite)
                { prop.SetValue(obj, "-", null); } 
                //else
                //{ prop.SetValue(obj, 0, null); }
            }
        }
        catch (Exception ex)
        {
            if (ex.InnerException != null)
            {
                throw ex.InnerException;
            }
        }

        e.NewItem = obj;
    }

这就是我希望每个属性都能工作的方式(LastChange是来自父类的静态字符串):

public string Provaa { get { return provaa; } 
set { LastChange = ToString(); provaa = value; OnPropertyChanged("Provaa"); } }

这就是如何转换为Msil:

.method public hidebysig specialname instance void 
    set_Provaa(string 'value') cil managed
{
// Code size       32 (0x20)
.maxstack  8
IL_0000:  nop
IL_0001:  ldarg.0
IL_0002:  callvirt   instance string [mscorlib]System.Object::ToString()
IL_0007:  stsfld     string EYBDataManager.DataObject::LastChange
IL_000c:  ldarg.0
IL_000d:  ldarg.1
IL_000e:  stfld      string EYBDataManager.Prova::provaa
IL_0013:  ldarg.0
IL_0014:  ldstr      "Provaa"
IL_0019:  call       instance void EYBDataManager.DataObject::OnPropertyChanged(string)
IL_001e:  nop
IL_001f:  ret
} // end of method Prova::set_Provaa

最后,这就是我尝试使用反射重新创建它的方式:

MethodBuilder currSetPropMthdBldr = typeBuilder.DefineMethod("set_value", GetSetAttr, null, new Type[] { prop.ActualType });
ILGenerator currSetIL = currSetPropMthdBldr.GetILGenerator();
currSetIL.Emit(OpCodes.Ldarg_0);
currSetIL.Emit(OpCodes.Callvirt, typeof(Object).GetMethod("ToString"));
currSetIL.Emit(OpCodes.Stsfld, typeof(DataObject).GetField("LastChange", BindingFlags.Static | BindingFlags.Public);
currSetIL.Emit(OpCodes.Ldarg_0);
currSetIL.Emit(OpCodes.Ldarg_1);
currSetIL.Emit(OpCodes.Stfld, field);
currSetIL.Emit(OpCodes.Ldarg_0);
currSetIL.Emit(OpCodes.Ldstr, propertyName);
currSetIL.Emit(OpCodes.Callvirt, typeof(DataObject).GetMethod("OnPropertyChanged", new Type[1] { typeof(string) }));
currSetIL.Emit(OpCodes.Ret);

是" CreateClass"的一部分。方法:

public static void CreateClass(string className, List<PropertyTemplate> properties)
{
AssemblyName assemblyName = new AssemblyName();
assemblyName.Name = "tmpAssembly";
AssemblyBuilder assemblyBuilder = System.Threading.Thread.GetDomain().DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Run);
ModuleBuilder module = assemblyBuilder.DefineDynamicModule("tmpModule");
TypeBuilder typeBuilder = module.DefineType(className, TypeAttributes.Public | TypeAttributes.Class, typeof(DataObject));

foreach (PropertyTemplate prop in properties)
{
    string propertyName = prop.Name;
    FieldBuilder field = typeBuilder.DefineField("p_" + propertyName, prop.ActualType, FieldAttributes.Private);
    PropertyBuilder property = typeBuilder.DefineProperty(propertyName, PropertyAttributes.None, prop.ActualType, new Type[] { prop.ActualType });
    MethodAttributes GetSetAttr = MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.HideBySig;

    MethodBuilder currGetPropMthdBldr = typeBuilder.DefineMethod("get_value", GetSetAttr, prop.ActualType, Type.EmptyTypes);
    ILGenerator currGetIL = currGetPropMthdBldr.GetILGenerator();
    currGetIL.Emit(OpCodes.Ldarg_0);
    currGetIL.Emit(OpCodes.Ldfld, field);
    currGetIL.Emit(OpCodes.Ret);


    ILGenerator currSetIL = currSetPropMthdBldr.GetILGenerator();
    currSetIL.Emit(OpCodes.Ldarg_0);
    currSetIL.Emit(OpCodes.Callvirt, typeof(Object).GetMethod("ToString"));
    currSetIL.Emit(OpCodes.Stsfld, DataObject.LastChange);
    currSetIL.Emit(OpCodes.Ldarg_0);
    currSetIL.Emit(OpCodes.Ldarg_1);
    currSetIL.Emit(OpCodes.Stfld, field);
    currSetIL.Emit(OpCodes.Ldarg_0);
    currSetIL.Emit(OpCodes.Ldstr, propertyName);
    currSetIL.Emit(OpCodes.Callvirt, typeof(DataObject).GetMethod("OnPropertyChanged", new Type[1] { typeof(string) }));
    currSetIL.Emit(OpCodes.Ret);

    property.SetGetMethod(currGetPropMthdBldr);
    property.SetSetMethod(currSetPropMthdBldr);
}

Type genType = typeBuilder.CreateType();
if (Templates.ContainsKey(className))
    Templates[className] = genType;
else
    Templates.Add(className, genType);
}

我怀疑在设置值时我需要指定程序集名称和类的模块名称,但不知道如何,尽管Activator创建具有所有正确属性的类实例,所以我可能在构建SetMethod时犯了一些错误,有人可以帮帮我吗?

编辑父类:

    public class DataObject : INotifyPropertyChanged
{
    public static string LastChange = "";

    public void OnPropertyChanged(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }

    public override string ToString()
    {
        string tostring = "|";
        PropertyInfo[] properties = this.GetType().GetProperties();
        foreach (PropertyInfo prop in properties)
        {
            tostring += " " + prop.GetValue(this, null) + " |";
        }
        return tostring;
    }

    public event PropertyChangedEventHandler PropertyChanged;
}

1 个答案:

答案 0 :(得分:1)

我在你的setter IL代码中看到两个错误

此:

currSetIL.EmitCall(OpCodes.Call, typeof(Object).GetMethod("ToString"), new Type[0]);

需要:

currSetIL.Emit(OpCodes.Callvirt, typeof(Object).GetMethod("ToString"), new Type[0]);

而且:

currSetIL.Emit(OpCodes.Ldstr, propertyName);
currSetIL.Emit(OpCodes.Call, typeof(DataObject).GetMethod("OnPropertyChanged", new Type[1] { typeof(string) }));

需要:

currSetIL.Emit(OpCodes.ldarg_0);
currSetIL.Emit(OpCodes.Ldstr, propertyName);
currSetIL.Emit(OpCodes.Callvirt, typeof(DataObject).GetMethod("OnPropertyChanged", new Type[1] { typeof(string) }));

我在第一种情况下看到您将callvirt置于评论中,并将其替换为call为什么?它是对虚拟方法的调用。

另外在第二种情况下,它的虚拟呼叫,你忘了先加载this来调用实例方法OnPropertyChanged

这就是我现在所看到的,让我知道它是否已修复,如果没有,我会尝试在自己身上重现它。

<强>更新

替换它:

currSetIL.Emit(OpCodes.Stsfld, DataObject.LastChange)

有了这个:

currSetIL.Emit(OpCodes.Stsfld, typeof(DataObject).GetField("LastChange", BindingFlags.Static | BindingFlags.Public)