在接口的泛型方法中使用泛型类型的参数

Question

my friends. I'm new to generics, but want to create interface (let it be IFooAsync) with generic method (FooAsync) that gets parameter of another generic type (that has definition Process), but I don't want to include this U type in method definition. How to do that right? My code now looks like this (I've used Object as generic Progress type, but sure it's an awful solution):

public interface IFooAsync
{
    System.Threading.Tasks.Task<List<T>> FooAsync<T>(
        // Some parameters, that my method gonna take.
        System.IProgress<Object> progress,
        System.Threading.CancellationToken cancellationToken) where T : new();
}

Answer 1

You could do

using System;
using System.Threading;
using System.Threading.Tasks;

public interface IFooAsync<TReturn> where TReturn : new()
{
    Task<List<TReturn>> FooAsync<TProgress>(IProgress<TProgress> progress, 
                                            CancellationToken cancellationToken);
}

which means you don't have to specify two type paremeters when calling the method as the compiler can infer them.

eg

IFooAsync<string> myFoo = ... ;
IProgress<int> myProgress = ... ;

List<string> result = await myFoo.FooAsync(myProgress, CancellationToken.None);