The type arguments for method cannot be inferred from the usage

Question

Maybe I'm overworked, but this isn't compiling (CS0411). Why?

interface ISignatur<T>
{
    Type Type { get; }
}

interface IAccess<S, T> where S : ISignatur<T>
{
    S Signature { get; }    
    T Value { get; set; }
}

class Signatur : ISignatur<bool>
{
    public Type Type
    {
        get { return typeof(bool); }
    }
}

class ServiceGate
{
    public IAccess<S, T> Get<S, T>(S sig) where S : ISignatur<T>
    {
        throw new NotImplementedException();
    }
}

static class Test
{
    static void Main()
    {
        ServiceGate service = new ServiceGate();
        var access = service.Get(new Signatur()); // CS4011 error
    }
}

Anyone an idea why not? Or how to solve?

Answer 1

Get<S, T> takes two type arguments. When you call service.Get(new Signatur()); how does the compiler know what T is? You'll have to pass it explicitly or change something else about your type hierarchies. Passing it explicitly would look like:

service.Get<Signatur, bool>(new Signatur());