What is the purpose of the PropertySpecified pattern used by XML Serialization?

What is the purpose of the PropertySpecified pattern used by XML Serialization ?

What problem doe开发者_开发技巧s it tryto solve ?

---

It tries to solve the problem that int float and so on cannot be null, so it has no other way to signal whether the attribute/element exists in the XML file or not.

It was really only useful in .NET 1.x, since in .NET 2 you can just use Nullable<T> (e.g. int?) instead.