Proposal Async "while" syntactic sugar

[BrianCArnold]

Currently, to fire an async task and perform actions while it is completing, one usually does this:

var valueRetrievalTask = RetrieveValueAsync(someRelatedValue));
SynchronousMethod1();
SynchronousMethod2();
var retrievedValue = await valueRetrievalTask;

This requires that a task variable, and separates the assignment from the invocation of the async task.

I propose syntax similar to the following:

var retrievedValue = while(RetrieveValueAsync(someRelatedValue))
{
SynchronousMethod1();
SynchronousMethod2();
};

This allows the developer to see the assignment directly next to the invocation, and decoratively associates what executes during the async task.

[CyrusNajmabadi]

while would be somewhat undesirable as it conveys 'looping'. Something which is not happening here.

This allows the developer to see the assignment directly next to the invocation,

Note: you get this even with the original code. i.e.:

var valueRetrievalTask = RetrieveValueAsync(someRelatedValue));

The variable, assignment, and invocation are all grouped together.

[svick]

I think you could get fairly close to your desired syntax by using a helper method and a lambda:

var retrievedValue = await Meanwhile(RetrieveValueAsync(someRelatedValue), () =>
{
    SynchronousMethod1();
    SynchronousMethod2();
});

The implementation of Meanwhile would be:

static Task<T> Meanwhile<T>(Task<T> task, Action meanwhileAction)
{
    meanwhileAction();
    return task;
}