枚举器中使用的这种设计模式是什么。?

public class Versioned
{
    internal int version = 0;

    public void ThisBreaksVersion()
    {
        version++;
    }
}

public class WorksOnVersioned
{
    private readonly int version;
    private readonly Versioned versioned;

    public WorksOnVersioned(Versioned versioned)
    {
        this.versioned = versioned;
        this.version = versioned.version;
    }

    public void DoWork()
    {
        if( version != other.version )
            throw new Exception(); // Ooop.. Out of sync!
    }
}


var v1 = new Versioned();
var w1 = WorksOnVersioned(v1);
w1.DoWork(); // Yup

var v2 = new Versioned();
var w2 = WorksOnVersioned(v2);
v2.ThisBreaksVersion();
w2.DoWork(); // v2 has changed -> exception!

在使用共享资源以确保本地副本与资源中的副本相同时,我还可以看到这一点很有用。

但这种模式叫什么?它还有什么用处吗?