C# const



http://msdn.microsoft.com/zh-cn/library/e6w8fe1b.aspx

http://msdn.microsoft.com/zh-cn/library/ms173119(v=vs.120).aspx

http://blogs.msdn.com/b/ericlippert/archive/2007/11/13/immutability-in-c-part-one-kinds-of-immutability.aspx