如何使用带有Setter的System.Lazy对POCO实体中的列表进行延迟初始化？ [英] How to use System.Lazy with Setter to Lazy Initialization of List in POCO Entities?

问题描述

我想在实体中使用System.Lazy到Lazy初始化我的列表：

I want to use System.Lazy to Lazy Initialization of my List in my Entites:

public class Questionary
{
    private Lazy<List<Question>> _questions = new Lazy<List<Question>>(() => new List<Question>());

    public IList<Question> Questions { get { return _questions.Value; } set { _questions.Value = value; } }
}

问题出在我的SETTER上，出现此错误：属性' System.Lazy< T> .Value '没有设置器

The problem is on my SETTER, get this error: The property 'System.Lazy<T>.Value' has no setter

如果我想要做 MyInstance.Questions = new List< Question> {...} ？

我该如何进行？

更新：

我正试图避免这种情况：

I'm trying to avoid that:

private IList<Question> _questions;

//Trying to avoid that ugly if in my getter:
public IList<Question> Questions { get { return _questions == null ? new List<Question>() : _questions; } set { _questions = value } }

我做错了吗？

推荐答案

您可以执行以下操作：

public class Questionary
{
    private Lazy<IList<Question>> _questions = 
        new Lazy<IList<Question>>(() => new List<Question>());

    public IList<Question> Questions
    {
        get { return _questions.Value; }
        set { _questions = new Lazy<IList<Question>>(() => value); }
    }
}

但是，我不明白为什么需要 Lazy< T> 都在这里。使用它没有好处，因为新 List< T> 的初始化应该与新 Lazy< T>的初始化相同; ...

However, I don't see why you need Lazy<T> here at all. There is no benefit in using it, because the initialization of a new List<T> should be the same as the initialization of a new Lazy<T>...

我认为保持它的简单性就足够了：

I think it would be enough to keep it as simple as this:

public class Questionary
{
    private IList<Question> _questions = new List<Question>();

    public IList<Question> Questions
    {
        get { return _questions; }
        set { _questions = value; }
    }
}

或

public class Questionary
{
    public Questionary()
    {
        Questions = new List<Question>();
    }

    public IList<Question> Questions { get; set; }
}

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