我正在使用Autofac。假设我有一个协变接口
interface IOptionFactory<out T> where T : IOption
和具体实施
class Option1Factory : IOptionFactory<Option1>
class Option2Factory : IOptionFactory<Option2>
我把它们注册为
container.RegisterType<Option1Factory>.As<IOptionFactory<Option1>>();
container.RegisterType<Option2Factory>.As<IOptionFactory<Option2>>();
有没有办法,如何解决IOptionFactory的所有实现?因为这是协变的,所以在C#中这应该是合法的(我是对的吗?)。就像是:
var factories = container.Resolve<IEnumerable<IOptionFactory<IOption>>>();
最好的解决方案是将代码包装在Reporting
类中,其中包含IEnumerable
的私有IOptionFactory<IOption>
属性。
private class Reporting
{
private IEnumerable<IOptionFactory<IOption>> _allOptionsFactories;
public Reporting(IEnumerable<IOptionFactory<IOption>> allOptionsFactories)
{
if (allOptionsFactories == null)
{
throw new ArgumentNullException("Parameter:" + nameof(allOptionsFactories));
}
this._allOptionsFactories = allOptionsFactories;
}
public void Report()
{
foreach (var optionsFactories in _allOptionsFactories)
{
Console.WriteLine(optionsFactories.GetType());
}
}
}
然后您可以注册并使用它们:
[TestMethod]
public void PassingParametersToRegister_NamedParameter()
{
ContainerBuilder builder = new ContainerBuilder();
builder.RegisterType<IOption1Factory1<SomeOption>>().As<IOptionFactory<IOption>>();
builder.RegisterType<IOption1Factory2<SomeOption>>().As<IOptionFactory<IOption>>();
builder.RegisterType<Reporting>();
using (var container = builder.Build())
{
container.Resolve<Reporting>().Report();
}
//OUTPUT:
//Enumerations + IOption1Factory1`1[Enumerations + SomeOption]
//Enumerations + IOption1Factory2`1[Enumerations + SomeOption]
}
这是我的github中的完整代码