C＃中：如何添加属性的对象在运行时？ [英] c#:How to add a attributes to an object at runtime？

问题描述

作为一个实体类，我想补充一个属性在运行时，我应该怎么办？

As an entity class, I want to add a attributes at runtime, how should I do?

推荐答案

有什么需要看到的属性？如果是像数据绑定等， TypeDescriptor 应该工作：

What needs to see the attributes? If it is things like data-binding etc, TypeDescriptor should work:

TypeDescriptor.AddAttributes(type, attribs);
TypeDescriptor.AddAttributes(instance, attribs);

这只会影响 System.ComponentModel 的使用（不是直接反映），但往往是不够的 - 例如，你可以关联一个类型转换器通过上面的。

This only affects System.ComponentModel usage (not direct reflection), but that is often enough - for example, you can associate a TypeConverter via the above.

如果通过属性你的意思是属性，然后（再次，就数据绑定而言） TypeDescriptor 也有潜在的有 - 但它是不-不重要的;你需要或者实施 ICustomTypeDescriptor 的对象，或者写一个 CustomTypeDescriptor 的类型 - 在这两种情况下，你需要编写自己的的PropertyDescriptor 执行（通常说给每个实例的字典等）。这将让使用任何用途：

If by "attributes" you mean "properties", then (again, as far as data-binding is concerned) TypeDescriptor also has potential there - but it is non-trivial; you need to either implement ICustomTypeDescriptor on the object, or to write a CustomTypeDescriptor for the type - and in either case, you need to write your own PropertyDescriptor implementation (often talking to a per-instance dictionary etc). This will get used by anything that uses:

// only works if you use TypeDescriptionProvider
PropertyDescriptorCollection typeProps = TypeDescriptor.GetProperties(type);
// works via TypeDescriptionProvider or ICustomTypeDescriptor
PropertyDescriptorCollection objProps = TypeDescriptor.GetProperties(obj);

再次，这涉及面广，数据绑定和类似的情景。对于这样的一个例子，<一href="http://groups.google.com/group/microsoft.public.dotnet.languages.csharp/msg/55ea254ad3c6abf6">see这里 - 它是远离琐碎，但是。该示例使用（从链接）在运行时增加了两个属性：

Again, this covers a wide range of data-binding and similar scenarios. For an example of this, see here - it is far from trivial, however. The example usage (from the link) adds two properties at runtime:

Bag.AddProperty<int>("TestProp", new DefaultValueAttribute(5)); 
Bag.AddProperty<string>("Name");

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