[英]Resolve Generic Interface with Simple Injector
Wondering if it's possible to achieve the following: 想知道是否有可能实现以下目标:
container.GetInstance<IWordFacade<,,,>>();
So far I haven't been able to. 到目前为止,我还没有。 Here are some code samples:
以下是一些代码示例:
IWordFacade<T1,T2,T3,T4>{
T1 DoSomething(T2);
}
public class ConcreteFacade1 : IWordFacade<int,long,double,decimal>{
int DoSomething(long param){
//....
}
}
public class ConcreteFacade2 : IWordFacade<short,string,float,char>{
short DoSomething(string param){
// ...
}
}
... given these types/classes I am trying to find something that will allow me to return either ConcreteFacade1 or 2 based on how the container is configured to resolve the interface (which is where I'm having trouble). ...给定这些类型/类我试图找到一些东西,允许我根据容器配置如何解析接口(这是我遇到麻烦的地方)返回ConcreteFacade1或2。
I have tried: 我试过了:
container.Register(typeof(IWordFacade<,,,>), typeof(ConcreteFacade1));
resulting in an error stating: IWordFacade<,,,> is not a registered open generic type. 导致错误说明:IWordFacade <,,,>不是注册的开放泛型类型。
The code you supplied is not valid C# and will not compile. 您提供的代码无效C#,无法编译。 You can't specify an open-generic type within the < and > tags.
您无法在<和>标记内指定开放泛型类型。 You have to specify a closed generic type.
您必须指定一个封闭的泛型类型。 The following however is valid C#:
但是以下是有效的C#:
container.GetInstance(typeof(IWordFacade<,,,>));
Although this would compile, this still will not work in Simple Injector (or any other DI framework), since frameworks always want to return you a concrete instance, but you can't create an instance for an open generic type, which is quite obvious, since an open-generic type is just a template. 虽然这会编译,但这仍然无法在Simple Injector(或任何其他DI框架)中工作,因为框架总是希望返回一个具体的实例,但是你不能为开放的泛型类型创建一个实例,这很明显,因为开放泛型类型只是一个模板。 You need to fill in the blanks to be able to create an instance.
您需要填写空白才能创建实例。 In other words, you need a closed-generic type.
换句话说,您需要一个封闭的泛型类型。
But how should the container know which closed-generic instance it should create given this open generic type? 但是,对于这个开放的泛型类型,容器应该如何知道应该创建哪个封闭通用实例? There is an endless number of possible permutations.
存在无数可能的排列。
Although you can register an open-generic type like this: 虽然您可以注册这样的开放泛型类型:
container.Register(typeof(IWordFacade<,,,>), typeof(WordImpl<,,,>));
You will have to request for a closed-generic interface for your DI container to be able to resolve it: 您必须为DI容器请求一个封闭的通用接口才能解决它:
container.GetInstance<IWordFacade<Foo, Bar, FooBar>>();
or 要么
container.GetInstance(typeof(IWordFacade<Foo, Bar, FooBar>));
UPDATE UPDATE
From your update I understand that there is that you either register ConcreteFacade1
or ConcreteFacade2
, based on the config file, but never both. 根据您的更新,我了解您可以根据配置文件注册
ConcreteFacade1
或ConcreteFacade2
,但不能同时注册。 To be able to do this (in C#) you need a non-generic interface, otherwise you will only be able to program against System.Object
, which is not very useful (and type-safe). 为了能够执行此操作(在C#中),您需要一个非泛型接口,否则您将只能对
System.Object
进行编程,而System.Object
不是非常有用(并且类型安全)。 So let your generic IWordFacade<T1,T2,T3,T4>
inherit from the following non-generic interface: 因此,让您的通用
IWordFacade<T1,T2,T3,T4>
继承自以下非通用接口:
interface IWordFacade {
object DoSomething(object value);
}
This way you can make the following registration: 这样您就可以进行以下注册:
contianer.Register<IWordFacade, ConcreteFacade1>();
And you can resolve: 你可以解决:
container.GetInstance<IWordFacade>();
Or of course inject IWordFacade
into the constructor of a different type. 或者当然将
IWordFacade
注入到不同类型的构造函数中。
You now need to implement two methods into the implementations. 您现在需要在实现中实现两个方法。 If you have several implementations, it gets useful to define a base class.
如果您有多个实现,那么定义基类会很有用。 This base class can implement the non-generic interface method:
该基类可以实现非泛型接口方法:
public abstract class WordFacadeBase<T1, T2, T3, T4> : IWordFacade<T1, T2, T3, T4> {
public abstract T1 DoSomething(T2 value);
object IWordFacade.DoSomething(object value) {
return DoSomething(T2)value);
}
}
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