I have a class that takes an interface a开发者_运维技巧s a constructor argument. There are two implementations of this interface and I want to decide what implementation to use at runtime based on a variable.
The problem is that the class above is deep in an object heirarchy that is resolved by Autofac and so I can't pass in the argument.
Somehing like below is what I am trying to achieve.
public interface IInterface1 {}
public interface IInterface2 {}
public class Class1 : IInterface2
{
public Class1(IInterface1 interface1)
{
}
}
public class Class2
{
public Class2(IInterface2 interface2)
{
}
}
public class Class3
{
public void GetClass2Instance(string interface1ImplementationToChoose)
{
// want to change which implementation of IInterface1 is resolved based on the interface1ImplementationToChoose variable
var class2 = container.Resolve<Class2>();
}
}
Any ideas?
UPDATE:
To clarify, this is an existing object hierarchy that is used by existing applications that work fine. Also, the object model is much larger than the one shown in this example. As a result I don't really want to have to pass down a factory to each constructor in the object graph to be used by a class deep in that graph.
Is there a way of getting a different implementation of IInterface1 passed into Class1 without Class2 knowing anything about it?
Thanks
Yes, inject a factory that hides how the types are chosen:
public class Class3
{
private Func<string, Class2> _class2Factory;
public Class3(Func<string, Class2> class2Factory)
{
_class2Factory = class2Factory;
}
public void GetClass2Instance(string interface1ImplementationToChoose)
{
var class2 = _class2Factory(interface1ImplementationToChoose);
}
}
And then the container setup, something along these lines:
builder.RegisterType<Implementation1>().Named("imp1").As<IInterface1>();
builder.RegisterType<Implementation2>().Named("imp2").As<IInterface1>();
builder.Register<Func<string, Class2>>(c =>
{
var context = c.Resolve<IComponentContext>();
return imp => new Class2(context.Resolve<IInterface1>(imp));
});
builder.RegisterType<Class3>();
You can now use Class3
like this:
public class Class4
{
public Class4(Class3 class3)
{
var class2with1 = class3.GetClass2Instance("imp1");
var class2with2 = class3.GetClass2Instance("imp2");
}
}
NOTE: I have assumed that you meant that Class2
should be injected with varying implementations of the same interface IInterface1
. Your sample is a bit confusing since you are showing two classes that implements different interfaces.
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