Question

I have a:

DateTime?[] dates

I need to convert to:

Double?[] oaDates

Any way to clean up this one liner? Or should I just resort to a function?

DateTime?[] dates = new DateTime?[]{DateTime.Now, DateTime.Now.AddDays(1), DateTime.Now.AddDays(2)}; //example array
Double?[] oaDates = dates.Select(t => (t==null)?((double?)null):(t??DateTime.MinValue).ToOADate()).ToArray();

I can’t call a method on t without checking that it’s null (hence the tertiary operator) and I have to coalesce it as well so that I can call OADate (hence the coalesce and filler DateTime.MinValue that will never be hit).

It gets the job done in one line, but it is looking a little perl-like.

Maybe an extension method? That way I can hide the ugliness and just do something along the lines of:

dates.ToNullableOADates();

Answer 1

You can actually call extension methods on null references. So you could define an extension method to convert a single DateTime? to a double? like:

public static class DateUtil
{
    public static double? ConvertToDouble(this DateTime? date)
    {
        return date.HasValue ? date.Value.ToOADate() : (double?)null;
    }
}

Then call it like:

double?[] oaDates = dates.Select(t => t.ConvertToDouble()).ToArray();

However, you could equally call it using the method group syntax:

double?[] oaDates1 = dates.Select(DateUtil.ConvertToDouble).ToArray();