C# using statement with return value or inline declared out result variable

Question

I am wondering if there is some way to optimize the using statement to declare and assign its output together (when it is a single value).

For instance, something similar to the new way to inline declare the result variable of an out parameter.

//What I am currently doing:
string myResult;
using(var disposableInstance = new myDisposableType()){
    myResult = disposableInstance.GetResult();
}

//That would be ideal
var myResult = using(var disposableInstance = new myDisposableType()){
    return disposableInstance.GetResult();
}

//That would be great too
using(var disposableInstance = new myDisposableType(), out var myResult){
    myResult = disposableInstance.GetResult();
}

Thanks for your input.

Answer 1

You can use extension method to "simplify" this usage pattern:

public static class Extensions {
    public static TResult GetThenDispose<TDisposable, TResult>(
        this TDisposable d, 
        Func<TDisposable, TResult> func) 
            where TDisposable : IDisposable {

        using (d) {
            return func(d);
        }
    }
}

Then you use it like this:

string myResult = new myDisposableType().GetThenDispose(c => c.GetResult());

Answer 2

This is funny, because I started reading Functional Programming in C# a couple of days ago, and one of the first examples is along the lines of:

public static TResult Using<TDisposable, TResult>(TDisposable disposable, Func<TDisposable, TResult> func) 
    where TDisposable : IDisposable
{
    using (disposable)
    {
        return func(disposable);
    }
}

Usage:

 var result = Using(new DbConnection(), x => x.GetResult());

Notice that, unlike the other answers posted, this function has absolutely no responsibility but get the result of func, regardless of TDisposable.