Tin Isles

Another quick one! Forcing myself to learn LINQ, so I decided to rewrite some looping code. The original code; simple enough, loop thru all the daylight adjustments for a timezone and build a list of date/time and offset.

List<TransitionOffset> transitions = new List<TransitionOffset>();
foreach (TimeZoneInfo.AdjustmentRule adj in TimeZoneInfo.FindSystemTimeZoneById("AUS Eastern Standard Time").GetAdjustmentRules())
{
    if (adj.DateEnd.Year >= 2010)
    {
        for (int year = 2010; year <= 2015; year++)
        {
            transitions.Add(new TransitionOffset
            {
                Transition = GetDateTime(year, adj.DaylightTransitionStart),
                Offset = adj.DaylightDelta.TotalHours
            });
            transitions.Add(new TransitionOffset
            {
                Transition = GetDateTime(year, adj.DaylightTransitionEnd),
                Offset = 0
            });

        }
    }
}
transitions = transitions.OrderBy(t => t.Transition).ToList();

..and again in LINQ

var zoneAdjs = from adj in TimeZoneInfo.FindSystemTimeZoneById("AUS Eastern Standard Time").GetAdjustmentRules()
                where adj.DateEnd.Year >= 2010
                from year in Enumerable.Range(2010, 6)
                let trans = new[] { 
                                        new { Transition = GetDateTime(year, adj.DaylightTransitionEnd), 
                                            Offset = 0.0},
                                        new { Transition = GetDateTime(year, adj.DaylightTransitionStart),
                                        Offset = adj.DaylightDelta.TotalHours}
                                    }
                from tran in trans
                orderby tran.Transition
                select tran;

Any more readable / maintainable than the non-LINQ version? It definitely took longer to write while I’m a LINQ “newbie”. The most complicated bit was pulling the DaylightTransitionEnd and DaylightTransitionStart into one collection. This collection is only ever used to create JSON, so I like being able to serialize anonymous types from LINQ, and skip creating classes that are only used to serialize.