Return indicator as async Task

[urbanchaman]

Hello! I'm pretty new to C#. I want to make a method to get the result history of any indicator. Something like this:

async Task<List> GetIndicator(Task<List> priceData, string name, int lookback)
{
var data = await priceData;
switch (name)
{
case "Adx":
return data.GetAdx(lookback);
break;
case "AtrStop":
return data.GetAtrStop(lookback);
break;
etc..
}
}

I just can't figure out what to use as return type. I'm sure this is because I don't know some basic C# stuff, but I would be more than greatful for a hint. Thank you very much!

[DaveSkender]

It looks like you're trying to setup an asynchronous threading pattern. The basic use of this ADX indicator is a static synchronous pattern that looks like this:

// get results synchronously (normal way)
IEnumerable<AdxResult> results =  quotes.GetAdx(lookbackPeriods);

Generally speaking, since there are no awaited aspects in this library, you wouldn't need to use an asynchronous pattern for indicators. In fact, it can be slower performance in most use cases. However, if you do have a good use case for asynchronous Task operations, here's a few ways to have it return as Task<T>.

Option 1: Use Task.Run() syntax (simplest)

var results = await Task.Run(() => quotes.GetAdx(lookbackPeriod));

// in your example, your swtich statement would look like:
case "Adx":
    return await Task.Run(() => data.GetAdx(lookback));
    break;
case "AtrStop":
    return await Task.Run(() => data.GetAtrStop(lookback));
    break;
...

Option 2: Create a reusable wrapper method

public static Task<IEnumerable<AdxResult>> GetAdxAsync(
    IEnumerable<Quote> quotes,
    int lookbackPeriod)
{
    return Task.Run(() => quotes.GetAdx(lookbackPeriod));
}

// use it asynchronously
var results = await GetAdxAsync(quotes, lookbackPeriod);

Option 3: Create a universal .AsAsync() extension method

While this approach will work and might seem like the simplest to implement widely, it doesn't perform as well asynchronously as the first two options.

// has to be defined in a static class
public static class HelperExtensions
{
    public static Task<IEnumerable<TResult>> AsAsync<TResult>(
        this IEnumerable<TResult> results) 
        where TResult : ISeries
    {
        return await Task.Run(() => results);
    }
}

// use it asynchronously with any indicator
var results = await quotes
    .GetAdx(lookbackPeriod)
    .AsAsync();