Question

I want something like this:

class Foo<T>{...}

class Boo<T>{

   Queue<T> stuff = new Queue<T>();

   public void Boo(Foo<T>){...};
}

...

//Extract the generic type - string - to define the type
//of MyBoo.
var MyBoo = new Boo(new Foo<string>());

I get the error “generic type ‘Boo’ requires ‘1’ type arguments. Ya, I fixed the problem by stating the template type explicitly, but I’d like to know if there was/is a way to extract that type implicitly, rather than having to state it explicitly.

This other post may be related, but I’m not sure.

Answer 1

You can’t do it implicitly directly with the constructor of a generic type, but you could from a generic method, e.g. in a non-generic class:

public static class Boo
{
    public Boo<T> Create<T>(Foo<T> foo)
    {
        return new Boo<T>(foo);
    }
}

Then:

// myBoo will be inferred to be of type Boo<string>
var myBoo = Boo.Create(new Foo<string>());

Of course, it doesn’t have to be another class called Boo – it could be something completely different, and it could be an instance method of something else:

var factory = new BooFactory();
var myBoo = factory.Create(new Foo<string>());

The important point is that it’s a generic method – type arguments can be inferred for generic methods, but not for generic types.