Question

我需要弄清楚如何将接口的实现注入自身。如下面的示例所示，我想递归使用add方法。

具有添加功能的简单界面

public interface IRecursiveFactory
{
    int Add(int number, int max = 10);
}

注入DI容器

container.For<IRecursiveFactory>().Use<RecursiveFactory>();

这是显而易见的实现，但不是递归的

public class RecursiveFactory : IRecursiveFactory
{
    public int Add(int number, int max = 10)
    {
        while (number < max)
        {
            number++;
            Console.WriteLine(number);
        }

        return number;
    }
}

这是一个递归示例，将不起作用，它返回错误Activation error occurred while trying to get an instance of type IRecursiveFactory

public class RecursiveFactory : IRecursiveFactory
{
    private readonly IRecursiveFactory _recursiveFactory;

    // Inject "self"
    public RecursiveFactory(IRecursiveFactory recursiveFactory)
    {
        _recursiveFactory = recursiveFactory;
    }

    public int Add(int number, int max = 10)
    {
        while (number < max)
        {
            // recurse
            var newNumber = number + 1;
            Console.WriteLine(newNumber);
            number = _recursiveFactory.Add(newNumber);
        }

        return number;
    }
}

Answer 1

结果证明，懒惰解决方案可以解决此问题，其他解决方案仍然很有趣，因为这显然是激活问题。

与懒惰一起工作的版本

public class RecursiveFactory : IRecursiveFactory
{
    private readonly Lazy<IRecursiveFactory> _recursiveFactory;

    public RecursiveFactory(Lazy<IRecursiveFactory> recursiveFactory)
    {
        _recursiveFactory = recursiveFactory;
    }

    public int Add(int number, int max = 10)
    {
        while (number < max)
        {
            var newNumber = number + 1;
            Console.WriteLine(newNumber);
            number = _recursiveFactory.Value.Add(newNumber);
        }

        return number;
    }
}

使用构造函数注入进行StructureMap递归

1 个答案: