向系统类添加自定义属性

发布于 2024-12-07 05:37:55 字数 219 浏览 2 评论 0原文

我想从 System.Activites.Presentation 我的自定义属性添加类。我尝试使用 emit(TypeBuilder, ModuleBuilder, AssemblyBuilder) 来实现。是否可以通过向现有类型添加属性来更改现有类型？或者如何告诉TypeBuilder，以便它使用现有的数据类型？或者从给定类型继承？谢谢。

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淡紫姑娘！ 2024-12-14 05:37:55

您无法向 System 类添加属性，但如果它们未标记为 Sealed，您可以创建从原始派生的自定义类并添加自定义属性。

您的所有代码都必须调用派生类，除了添加的属性之外，派生类与原始类相同。

[MyAttribute(DisplayName="Name shown")]
public class MyActivity: System.Activities.Activity
{
}
/// <summary>
/// Custom attribute definition
/// </summary>
[AttributeUsage(AttributeTargets.Class)]
public sealed class MyAttribute : System.Attribute
{


    /// <summary>
    /// Defines the attribute
    /// </summary>
         public string DisplayName { get; set; }
    /// <summary>
    /// Allow access to the attribute
    /// </summary>
    /// <param name="prop"></param>
    /// <returns></returns>
      public static string GetDisplayName(System.Reflection.MemberInfo prop)
    {
        string field = null;
        object[] attr = prop.GetCustomAttributes(false);
        foreach (object a in attr)
        {
            MyAttribute additional = a as MyAttribute;
            if (additional != null)
            {
                field = additional.DisplayName;
            }
        }
        return field;
    }


}

You can't add attributes to System classes but, if they are not marked as Sealed you can create your custom class deriving from original and adding custom attribute.

All your code must call derived class, that is identical to the original except on the attribute added.

[MyAttribute(DisplayName="Name shown")]
public class MyActivity: System.Activities.Activity
{
}
/// <summary>
/// Custom attribute definition
/// </summary>
[AttributeUsage(AttributeTargets.Class)]
public sealed class MyAttribute : System.Attribute
{


    /// <summary>
    /// Defines the attribute
    /// </summary>
         public string DisplayName { get; set; }
    /// <summary>
    /// Allow access to the attribute
    /// </summary>
    /// <param name="prop"></param>
    /// <returns></returns>
      public static string GetDisplayName(System.Reflection.MemberInfo prop)
    {
        string field = null;
        object[] attr = prop.GetCustomAttributes(false);
        foreach (object a in attr)
        {
            MyAttribute additional = a as MyAttribute;
            if (additional != null)
            {
                field = additional.DisplayName;
            }
        }
        return field;
    }


}

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