不变性和XML序列化 [英] Immutability and XML Serialization

问题描述

我有几个班，一旦他们设定初始值是不可改变的。埃里克利珀称这直写一旦不变性。

I have several classes that are immutable once their initial values are set. Eric Lippert calls this write-once immutability.

实施一次性写入不变性在C＃中通常是指通过构造函数设置的初始值。这些值初始化只读域。

Implementing write-once immutability in C# usually means setting the initial values via the constructor. These values initialize readonly fields.

但是，如果您需要序列化类像这样的XML，即使用的XmlSerializer或DataContractSerializer的，你必须有一个无参数的构造函数。

But if you need to serialize a class like this to XML, using either the XmlSerializer or the DataContractSerializer, you must have a parameterless constructor.

有没有人有关于如何解决此问题的建议吗？是与序列化更好地工作，还有其他形式的不变性

Does anyone have suggestions for how to work around this problem? Are there other forms of immutability that work better with serialization?

编辑：由于@Todd指出，DataContractSerializer的不需要参数的构造函数。根据MSDN上中的的DataContractSerializer文件，DataContractSerializer的不叫。目标对象的构造函数

As @Todd pointed out, the DataContractSerializer does not require a parameterless constructor. According to the DataContractSerializer documentation on MSDN, DataContractSerializer "does not call the constructor of the target object."

推荐答案

假设这是你的不可变的对象：

Assuming this is your "immutable" object :

public class Immutable
{
    public Immutable(string foo, int bar)
    {
        this.Foo = foo;
        this.Bar = bar;
    }

    public string Foo { get; private set; }
    public int Bar { get; private set; }
}

您可以创建一个虚拟类来表示序列化/反序列化过程中不可变对象

You can create a dummy class to represent that immutable object during serialization/deserialization :

public class DummyImmutable
{
    public DummyImmutable(Immutable i)
    {
        this.Foo = i.Foo;
        this.Bar = i.Bar;
    }

    public string Foo { get; set; }
    public int Bar { get; set; }

    public Immutable GetImmutable()
    {
        return new Immutable(this.Foo, this.Bar);
    }
}

当你有不可变类型的属性，不要 ŧ序列化，而是序列化DummyImmutable：

When you have a property of type Immutable, don't serialize it, and instead serialize a DummyImmutable :

[XmlIgnore]
public Immutable SomeProperty { get; set; }

[XmlElement("SomeProperty")]
public DummyImmutable SomePropertyXml
{
    get { return new DummyImmutable(this.SomeProperty); }
    set { this.SomeProperty = value != null ? value.GetImmutable() : null; }
}

OK，这是有点长了东西，看起来这么简单.. 。但它应该工作;）

OK, this is a bit long for something that looks so simple... but it should work ;)

这篇关于不变性和XML序列化的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！