如何编写一个属性来设置自动属性的默认值
我读过通过属性设置默认属性的帖子，该属性以 DefaultValue 结尾，用于设计模式或序列化。
但是，有没有一种方法可以编写一个属性来满足这些帖子的要求：将属性默认为某个值。
如果有一种方法——如何开始编写这样的属性？
谢谢， L-
I've read the post for setting default properties via an attribute, which end with DefaultValue is for Design Mode or Serialization.
BUT, is there a way to write an Attribute that will do what these posts require: default the property to some value.
If there is a way -- how would one start writing such an attribute?
Thanks,
L-
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基本上你不能。
不过，您可以在构造函数中设置默认值。
碰巧我最近确实实现了一些这样做的东西，但那是使用基于工厂的构造；工厂检查
[DefaultValue]并通过反射设置值。但属性不能导致任意代码执行，除非您使用像 PostSharp 这样的重写器。如果构造函数距离您的喜好太远，您将必须使用字段初始化程序并针对该字段编写
get/set。You can't, basically.
You can set the default in the constructor, though.
As it happens I did implement something that did this very recently, but that was using factory-based construction; the factory checked for
[DefaultValue]and set the value via reflection. But attributes can't cause arbitrary code execution unless you use a re-writer like PostSharp.If the constructor is too far away for your liking, you will have to use a field-initializer and write the
get/setagainst the field.不幸的是属性只是元数据，这意味着它们无法自行运行或执行某些操作。
但是，没有什么可以阻止您编写名称类似于
SetDefaultValues的扩展方法，该方法从属性中读取默认值并将它们分配给属性。我在最近的一个项目中做了类似的事情，事实证明这是一个不错的决定，因为它将以声明式样式定义的所有默认值保留在一个位置。
有一篇关于 CodeProject 的 有趣的文章，深入探讨了实施
的不同策略基于 [DefaultValue]的初始化并比较它们的性能。我建议你检查一下。Unfortunately attributes are just metadata, meaning they cannot run or do something on their own.
However nothing prevents you from writing an extension method with a name like
SetDefaultValuesthat reads default values from attributes and assigns them to properties.I've done a similar thing in a recent project, and it proved to be a good decision because it kept all default values defined in a declarative style in a single place.
There is an interesting article on CodeProject peering into different strategies for implementation of
[DefaultValue]-based initialization and comparing their performance. I suggest you check it out.