Passing Type to to method with generics

Question

Hi I am tryng to create a generic wrapper around Unity that will enable me to change IoC frameworks whenever I want without the need of

public static void RegisterTypes(IDependencyInjectionContainerWrapper container)
    {
        List<Type> types = LoadTypesFromAssemblies();
        foreach (var type in types)
        {
            var interfaceType= type.CustomAttributes
                                 .FirstOrDefault(a => a.AttributeType.Name == typeof(DependencyService).Name)
                                 .ConstructorArguments[0].Value;

            container.RegisterType<type, interfaceType>();
        }
    }

What's happening here is I am getting a list types to with the attribute DependencyService is applyed.

Then I iterate over it and I am getting the first constructor argument of the attribute.

I am then attempting to Register the type in the container threw generics.This is where I am having problems.

I do not know how to pass the two types I have in the RegisterType method generics.As it stands I am getting errors because I am passing in the generic a variable not an object type

Is there anyway to solve my problem?

Answer 1

If the dependency container has a non-generic method, call that:

container.RegisterType(type, interfaceType);

If it doesn't have a non-generic method, and if you can modify the source, I'd strongly recommend providing one; it makes this kind of thing a lot easier. Typically, with a container like this your generic method will end up calling your non-generic one:

public void RegisterType(Type implType, Type ifaceType)
{
    ...
}

public void RegisterType<TImpl, TIface>() where TImpl : TIface
{
    this.RegisterType(typeof(TImpl), typeof(TIface));
}

Otherwise you'll have to dynamically provide the generic parameters through reflection:

var methodInfo = container.GetType().GetMethod("RegisterType");
var actualMethod = methodInfo.MakeGenericMethod(type, interfaceType);
methodInfo.Invoke(container);

But this is neither efficient nor particular elegant.

Answer 2

Use MethodInfo.MakeGenericMethod.