传递带有参数Func的方法 <T> 并获得TResult

Question

So basically T has a return type, I want to get back the generic return type. Example:

private TResult EndInvoke<T, TResult>(Func<T, TResult> asyncCaller, IAsyncResult asyncResult)
{
    TResult result = default(TResult);

    try
    {
        result = asyncCaller.EndInvoke(asyncResult);
    }
    catch (Exception exception)
    {
       // get exception details.
    }

    return result;
}

How do I pass just the T calling the method and get the TResult? Mind you, I only have the T.

EDIT: I meant how do I call this method?

EDIT: I want a generic EndInvoke, because I am a huge try catch on different EndInvokes, then I want the result from the EndInvoke.

Answer 1

I suggest converting your generic EndInvoke<,> method to an extension method first.

public static class FuncExtensions
{
    public static TResult EndInvoke<T, TResult>(this Func<T, TResult> asyncCaller, IAsyncResult asyncResult)
    {
        // ...
    }
}

This will simplify the method call. As an example, I'll call a method that calculates the square of an integer.

private int Square(int x)
{
    return x * x;
}

In your client code, you'd call it like this:

Func<int, int> caller = new Func<int, int>(Square);

int x = 5;

int y = default(int);

caller.BeginInvoke(x,
    asyncResult =>
    {
        y = caller.EndInvoke(asyncResult);
    },
    null);

Console.WriteLine("The square of {0} is {1}", x, y);

EDIT

This example has not been tested in any way, and contains an obvious race condition.

Answer 2

Not sure that I understand correctly, but I think that if you want the Func return value, you should drop the IAsyncResult.

Example:

private TResult GetResult<T, TResult>(Func<T, TResult> asyncCaller, IAsyncResult asyncResult)
    {
        TResult result = default(TResult);
        result = asyncCaller(argument...);

        return result;
    }