问题描述
我想知道在.net中的属性的使用，特别是C＃，无论是昂贵的，为什么或者为什么不？
I would like to know whether the usage of Attributes in .Net, specifically C#, is expensive, and why or why not?
我问有关C＃具体而言，除非有不同的.NET语言之间没有什么区别（因为基类库是一样的吗？）。
I am asking about C# specifically, unless there is no difference between the different .Net languages (because the base class libraries are the same?).
所有的新的.Net技术广泛使用的属性，如LINQ到SQL，ASP.Net MVC，WCF，企业库等，我想知道什么样的影响，这将有表现。该班的很多都会自动具有特定属性的装饰，或者需要某些功能/特性这些属性。
All the newer .Net technologies make extensive use of attributes, such as Linq to SQL, ASP.Net MVC, WCF, Enterprise Library, etc, and I was wondering what effect this would have on performance. Alot of the classes get automatically decorated with certain Attributes, or these attributes are required for certain functionality/features.
难道费用的问题取决于执行的具体细节？如何被编译为IL的属性？他们是自动缓存，或者是这件事的实现者？
Does the question of expense depend on implementation specific details? How are Attributes compiled to IL? Are they cached automatically, or is this up to the implementor?
推荐答案
属性的用法太模糊。取回的属性是反射操作有效的 - 你不会希望定期做一个循环 - 但他们没有昂贵的元数据包括，和典型使用模式（IMO）是建立其他一些重$ P看完属性后一度$ psentation（例如在内存架构）。
"The usage of attributes" is too vague. Fetching the attributes is a reflection operation effectively - you wouldn't want to regularly do it in a loop - but they're not expensive to include in the metadata, and the typical usage pattern (IMO) is to build some other representation (e.g. an in-memory schema) after reading the attributes once.
有可能是一些涉及到高速缓存，但我可能会缓存等再presentation反正。举例来说，如果我有描述装饰枚举值，我一般取属性的一次的建立一个字符串枚举字典（反之亦然）。
There may well be some caching involved, but I'd probably cache the other representation anyway. For example, if I were decorating enum values with descriptions, I'd generally fetch the attributes once to build a string to enum dictionary (or vice versa).
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