克隆/複製get訪問身體新型

Question

我是從現有類型創建動態裝配新的類型，但只有選擇的屬性包括：

public class EmitTest 
{ 
    public Type Create(Type prototype, Type dynamicBaseType, List<string> includedPropertyList) 
    { 
     AssemblyName aName = new AssemblyName("DynamicAssembly"); 
     AssemblyBuilder assemblyBuilder = AppDomain.CurrentDomain.DefineDynamicAssembly(
       aName, 
       AssemblyBuilderAccess.RunAndSave); 

     ModuleBuilder modulBuilder = assemblyBuilder.DefineDynamicModule(aName.Name, aName.Name + ".dll"); 


     string typeName = string.Concat(prototype.Name, "_DynamicType_", Guid.NewGuid().ToString().Replace("-", string.Empty)); 

     TypeBuilder typeBuilder = modulBuilder.DefineType(
      typeName, 
      TypeAttributes.Public, null, new Type[] { }); 

     foreach (string s in includedPropertyList) 
     { 
      PropertyInfo propertyInfo = prototype.GetProperty(s); 

      if (propertyInfo != null && dynamicBaseType.GetProperty(s) == null) 
      { 
       CreateProperty(typeBuilder, propertyInfo); 
      } 
     } 

     return typeBuilder.CreateType(); 
    } 

    #region Property Creation 

    private void CreateProperty(TypeBuilder typeBuilder, PropertyInfo propertyInfo) 
    { 
     PropertyBuilder propertyBuilder = typeBuilder.DefineProperty(
      propertyInfo.Name, 
      PropertyAttributes.HasDefault, 
      propertyInfo.PropertyType, 
      null); 

     CreatePropertyBase(typeBuilder, propertyBuilder, propertyInfo); 

     AddAttribute<BrowsableAttribute>(propertyBuilder, propertyInfo, CreatePropertyAttributeBrowsable); 
     AddAttribute<DisplayNameAttribute>(propertyBuilder, propertyInfo, CreatePropertyAttributeDisplayName);   
    } 

    private void CreatePropertyBase(TypeBuilder typeBuilder, PropertyBuilder propertyBuilder, PropertyInfo propertyInfo) 
    { 

     FieldBuilder fieldBuilder = typeBuilder.DefineField(
      string.Concat("m_", propertyInfo.Name), 
      propertyInfo.PropertyType, 
      FieldAttributes.Private); 

     MethodAttributes getSetAttr = MethodAttributes.Public | 
      MethodAttributes.SpecialName | MethodAttributes.HideBySig; 


     MethodBuilder mbGetAccessor = typeBuilder.DefineMethod(
      string.Concat("get_", propertyInfo.Name), 
      getSetAttr, 
      propertyInfo.PropertyType, 
      Type.EmptyTypes); 

     ILGenerator mbGetIL = mbGetAccessor.GetILGenerator(); 
     mbGetIL.Emit(OpCodes.Ldarg_0); 
     mbGetIL.Emit(OpCodes.Ldfld, fieldBuilder); 
     mbGetIL.Emit(OpCodes.Ret); 


     MethodBuilder mbSetAccessor = typeBuilder.DefineMethod(
      string.Concat("set_", propertyInfo.Name), 
      getSetAttr, 
      null, 
      new Type[] { propertyInfo.PropertyType }); 

     ILGenerator mbSetIL = mbSetAccessor.GetILGenerator();   
     mbSetIL.Emit(OpCodes.Ldarg_0); 
     mbSetIL.Emit(OpCodes.Ldarg_1); 
     mbSetIL.Emit(OpCodes.Stfld, fieldBuilder); 
     mbSetIL.Emit(OpCodes.Ret); 

     propertyBuilder.SetGetMethod(mbGetAccessor); 
     propertyBuilder.SetSetMethod(mbSetAccessor); 
    } 

    #endregion Property Creation 

    #region Attribute Createion 

    private void AddAttribute<T>(PropertyBuilder propertyBuilder, PropertyInfo propertyInfo, Action<PropertyBuilder, T> action) 
     where T : Attribute 
    { 
     T attribute = ReflectionHelper.GetAttribute(propertyInfo, typeof(T), false) as T; 

     if (attribute != null) 
     { 
      action(propertyBuilder, attribute); 
     } 
    } 

    private void CreatePropertyAttributeBrowsable(PropertyBuilder propertyBuilder, BrowsableAttribute browsableAttribute) 
    { 
     ConstructorInfo myAttrCtor = typeof(BrowsableAttribute).GetConstructor(new Type[] { typeof(bool) }); 
     CustomAttributeBuilder myAttr = new CustomAttributeBuilder(myAttrCtor, new object[] { browsableAttribute.Browsable }); 
     propertyBuilder.SetCustomAttribute(myAttr); 
    } 

    private void CreatePropertyAttributeDisplayName(PropertyBuilder propertyBuilder, DisplayNameAttribute displayNameAttribute) 
    { 
     ConstructorInfo myAttrCtor2 = typeof(DisplayNameAttribute).GetConstructor(new Type[] { typeof(string) }); 
     CustomAttributeBuilder myAttr2 = new CustomAttributeBuilder(myAttrCtor2, new object[] { displayNameAttribute.DisplayName }); 
     propertyBuilder.SetCustomAttribute(myAttr2); 
    } 

    #endregion Attribute Createion 
} 

這一切的偉大工程，但在這裏我只創建獲取或設置私有字段的簡單屬性。

我遇到了更復雜屬性的情況，例如在getter中有類似「A + B * C」的地方，其中A，B和C是屬於同一類的屬性。

我試圖像這樣創造CreatePropertyBase getter方法的副本：

 MethodBuilder mbNumberGetAccessor = typeBuilder.DefineMethod(
      string.Concat("get_", propertyInfo.Name), 
      getSetAttr, 
      propertyInfo.PropertyType, 
      Type.EmptyTypes);  


     System.Reflection.MethodInfo mi = propertyInfo.GetGetMethod(); 
     byte[] body = mi.GetMethodBody().GetILAsByteArray(); 

     mbNumberGetAccessor.CreateMethodBody(body, body.Length); 

這顯然沒有奏效。 :)

我的問題是：是否有可能複製身體的get訪問器，引用同一類中的其他屬性，並且如果可能的話該怎麼做。 我正在使用.NET 3.5 SP1

謝謝。

Answer 1

不，您必須從源屬性動態反編譯IL，因爲源屬性中的IL將具有對其引用的其他屬性的靜態PropertyInfo引用。而那些引用將是原始的PropertyInfo而不是你最近創建的，這可能是爲什麼它給你錯誤。

出於好奇，你不只是使用匿名類型做同樣的事情的原因是什麼？

Answer 2

你可以使用這個幫手（CIL Reader）有必要的修改，以遍歷屬性訪問的機構和重建他們