給類動態新增Attribute一直是我想要解決的問題,從msdn裡找了很久,到Stack Overflow看了不少文章,算是最終有了答案。
先是有這樣的一段解釋
Attributes are static metadata. Assemblies, modules, types, members, parameters, and return values aren't first-class objects in C# (e.g., the System.Type class is merely a reflected representation of a type). You can get an instance of an attribute for a type and change the properties if they're writable but that won't affect the attribute as it is applied to the type.
從這裡看,想要實現動態新增Attribute就是不可能做到的。哈哈,被標題坑了吧。
好吧,但是我還是找到了一個東西System.ComponentModel.TypeDescriptor,這個號稱可以新增Attribute到類、物件中去的類。TypeDescriptor裡有方法:AddAttributes,可以把Attribute新增到類上。但是隻有一個問題,新增上去的Attribute,只能通過TypeDescriptor來取到。
/* * 現在需要給simpleObject新增attribute */ TypeDescriptor.AddAttributes(typeof(targetObject), new simpleAttribute(new targetObject())); AttributeCollection collection = TypeDescriptor.GetAttributes(typeof(targetObject)); simpleAttribute attr = ((simpleAttribute)collection[typeof(simpleAttribute)]); if (attr != null) { MessageBox.Show(attr.ToString()); }