Brendan Tompkins [MVP]

First of all, I have to proclaim my love for the System.DateTime and System.TimeSpan object.  I have to say that other than System.Data.DataSet family of objects, they're my favorite.  The thing I like most, is that they give you just enough to usefully and easily extend the functionality, without being bloated and hard to understand.  A sincere thanks to the people involved in making them easy to use.

As an example, I needed recently needed a bunch of  date calculations, like WorkWeekStart, WorkWeekEnd, etc.  I came up with the following enum and method which I can use to derive all sorts of date caluclations:

public enum DateDirection
{
    Forward,
    Backward
}

public static DateTime GetDay(System.DayOfWeek dayOfWeek, int numberWeeks, DateDirection direction, bool dayEnd)
{
    // Get the initial date.
    DateTime checkDate = DateTime.Today;

    // If today's not the day we're looking for, loop and find the date
    if(!(checkDate.DayOfWeek == dayOfWeek && numberWeeks == 0))
    {
        int i = 0;
        // Loop for number of weeks...
        do
        {
            // Go forward or back one day..
            checkDate = (direction == DateDirection.Backward) ? checkDate.AddDays(-1) : checkDate.AddDays(1);
            // Loop until we find the correct day
            while(checkDate.DayOfWeek != dayOfWeek) 
            {
                checkDate = (direction == DateDirection.Backward) ? checkDate.AddDays(-1) : checkDate.AddDays(1);
            }
        } while(i++ < numberWeeks); // Loop for the number of weeks.
    }
    
    // If we need the end of the day, add the ticks to get us there.
    if(dayEnd) checkDate = checkDate.AddTicks(System.TimeSpan.TicksPerDay - 1);
    return checkDate;
}

Using this one method, I can derive all sorts of date calculations, like so:

/// <summary>
/// Start of week is Sunday 12:00 am
/// </summary>
public static DateTime WeekStart
{
    get { return GetDay(DayOfWeek.Sunday, 0, DateDirection.Backward);}
}

/// <summary>
/// Saturday at 11:59:59
/// </summary>
public static DateTime WeekEnd
{
    get { return GetDay(DayOfWeek.Saturday, 0, DateDirection.Forward, true); }
}

Ever tried doing this sort of thing with other frameworks?  Uggh!  The ease with which I was able to do this, was really one of those things that makes me a true-beliver in the .NET framework.

-Brendan