Question

我有以下课程：

[MetadataAttribute]
[AttributeUsage(AttributeTargets.Property, AllowMultiple = false)]
public class ModuleActivationButtonAttribute : ExportAttribute
{
    public Enum TargetRegion { get; set; }

    public ModuleActivationButtonAttribute(Enum targetRegion) : base(typeof(IModuleActivationButton))
    {
        TargetRegion = targetRegion;
    }
}

该类编译得很好，但当我用它装饰我的属性时：

[ModuleActivationButton(Regions.Tabs)]
public IModuleActivationButton ModuleActivationButton
{
    get { return new ModuleActivationButton() as IModuleActivationButton; }
    set { ModuleActivationButton = value; }
}

public enum Regions
{
    Content,
    Tabs
}

编译器吐出：

Error 1 An attribute argument must be a constant expression, typeof expression or array creation expression of an attribute parameter type C:\...\CompanyX.Modules.Home\HomeModule.cs 28 33 CompanyX.Modules.Home

Answer 1

似乎我可以将enum包装到一个对象并将其作为那个传递，然后是unbox。但是，我只能通过抛出异常来强制执行此操作，如果解释它不会取消装入Enum

[MetadataAttribute]
[AttributeUsage(AttributeTargets.Property, AllowMultiple = false)]
public class ModuleActivationButtonAttribute : ExportAttribute
{
    public Enum TargetRegion { get; set; }

    public ModuleActivationButtonAttribute(object targetRegion) : base(typeof(IModuleActivationButton))
    {
        TargetRegion = targetRegion as Enum;
    }
}

C＃ - Silverlight - 带Enum的CustomAttribute

1 个答案: