如何克隆Collection< T&gt ;？ [英] How do I clone a Collection<T>?

问题描述

我有一个枚举 Fruit 和一个类 FruitCollection ，该类派生了集合<水果> 。我找不到使用.NET克隆 FruitCollection 的方法，我发现了此MSDN文章定义了 DeepClone（ ）函数，并使用了 MemberwiseClone（）。现在，由于这是一个枚举，因此我不需要克隆它，因此我认为 MemberwiseClone（）就足够了。但是，当我在PowerShell中尝试时，克隆的对象似乎只是指向原始对象的指针，而不是克隆对象。我在做什么错？

I have an enumeration, Fruit, and a class, FruitCollection, which derives Collection<Fruit>. I couldn't find a way to clone FruitCollection using .NET and I found this MSDN article which defined a DeepClone() function and used MemberwiseClone(). Now, since this is an enumeration, I don't think I need to "deep" clone it, so I thought MemberwiseClone() would be sufficient. However, when I try it in PowerShell, the cloned object seems to simply be a pointer to the original object and not a clone. What am I doing wrong?

还有另一种方法可以简单地克隆 Collection 吗？ FruitCollection 没有其他自定义成员。

Is there another way to simply clone a Collection? FruitCollection has no other custom members.

C＃代码：

public enum Fruit
{
    Apple = 1,
    Orange = 2
}

public class FruitCollection : Collection<Fruit>
{
    public FruitCollection Clone()
    {
        return Clone(this);
    }

    public static FruitCollection Clone(FruitCollection fruitCollection)
    {
        return (FruitCollection)fruitCollection.MemberwiseClone();
    }

}

PowerShell输出：

PowerShell Output:

PS> $basket1 = New-Object TestLibrary.FruitCollection
PS> $basket1.Add([TestLibrary.Fruit]::Apple)
PS> $basket2 = $basket1.Clone()
PS> $basket1.Add([TestLibrary.Fruit]::Orange)
PS> $basket2
Apple
Orange

推荐答案

正如其他人在评论中指出的那样，您可以使用Collection上已经存在的构造函数，然后在 Clone 中，为要使用的新Collection创建一个新列表，以便

As others have pointed out in the comments, you can use the constructor that already exists on Collection and then in your Clone, create a new list for the new Collection to use so adding to basket1 doesn't affect basket2 and so forth.

public class FruitCollection : Collection<Fruit>
{
    public FruitCollection(IList<Fruit> source) : base(source)
    {
    }

    public FruitCollection()
    {
    }

    public FruitCollection Clone()
    {
        return Clone(this);
    }

    public static FruitCollection Clone(FruitCollection fruitCollection)
    {
        // ToList() will give a new List. Otherwise Collection will use the same IList we passed.
        return new FruitCollection(fruitCollection.ToList());
    }

}

void Main()
{
    var basket1 = new FruitCollection();
    basket1.Add(Fruit.Apple);
    var basket2 = basket1.Clone();
    basket2.Add(Fruit.Orange);
    Console.WriteLine("{0}", basket1.Count);
    Console.WriteLine("{0}", basket2.Count);
}

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