在 DryIoc DI-Container 中解析命名服务

Question

考虑以下两个 class：

public class Number
{
    public int Value { get; set; }
}

public class Multiplier
{
    private readonly Number first;
    private readonly Number second;

    public Multiplier(Number first, Number second)
    {
        this.first = first;
        this.second = second;
    }

    public int Multiply() => this.first.Value * this.second.Value;
}

classMultiplier 取决于 Number 的两个实例。我想使用 DryIoc DI-Container 将它们作为 named services 注入。执行此操作的代码如下所示：

var container = new Container();

container.RegisterInstance(new Number{Value = 2}, serviceKey:"first");
container.RegisterInstance(new Number{Value = 4}, serviceKey:"second");
container.Register<Multiplier>();

var consumer = container.Resolve<Multiplier>();

Console.WriteLine(consumer.Multiply());

由于注册实例无法解析为构造函数参数。我的问题基本上是：有什么方法可以让我指定哪个命名的 serviceKey 应该解析为哪个构造函数参数？

在 MEF 中，我将执行以下操作来实现此目的：

[Export(typeof(Multiplier))]
public class Multiplier
{
    private readonly Number first;
    private readonly Number second;

    [ImportingConstructor]
    public Multiplier([Import("first")]Number first, 
                      [Import("second")]Number second)
    {
        this.first = first;
        this.second = second;
    }

    public int Multiply() => this.first.Value * this.second.Value;
}

然后使用服务名称导出依赖项：

var container = new CompositionContainer(someCatalog);
container.ComposeExportedValue("first", new Number{Value = 2});
container.ComposeExportedValue("second", new Number{Value = 4});

var multi = container.GetExport<Multiplier>();

如何使用 DryIoc 执行此操作？

Answer 1

首先，您可以使用 DryIoc.MefAttributedModel.dll 扩展重用相同的 MEF 代码。

单独使用DryIoc，需要指定参数名（或Type，或位置）与servicKey:

的映射关系

var container = new Container();

container.RegisterInstance(new Number {Value = 2}, serviceKey:"first");
container.RegisterInstance(new Number {Value = 4}, serviceKey:"second");

container.Register<Multiplier>(made: Parameters.Of
    .Name("first",  serviceKey: "first")
    .Name("second", serviceKey: "second"));

var consumer = container.Resolve<Multiplier>();

此处有更多详细信息：https://github.com/dadhi/DryIoc/blob/master/docs/DryIoc.Docs/SpecifyDependencyAndPrimitiveValues.md#complete-example-of-matching-the-parameter-name-to-the-service-key

在 DryIoc DI-Container 中解析命名服务

Resolving named services in DryIoc DI-Container

c#

dependency-injection

mef

dryioc