Non sono sicuro esattamente quello che' sto cercando, ma questo programma:
public class Building
{
public enum StatusType
{
open,
closed,
weird,
};
public string Name { get; set; }
public StatusType Status { get; set; }
}
public static List <Building> buildingList = new List<Building>()
{
new Building() { Name = "one", Status = Building.StatusType.open },
new Building() { Name = "two", Status = Building.StatusType.closed },
new Building() { Name = "three", Status = Building.StatusType.weird },
new Building() { Name = "four", Status = Building.StatusType.open },
new Building() { Name = "five", Status = Building.StatusType.closed },
new Building() { Name = "six", Status = Building.StatusType.weird },
};
static void Main (string [] args)
{
var statusList = new List<Building.StatusType>() { Building.StatusType.open, Building.StatusType.closed };
var q = from building in buildingList
where statusList.Contains (building.Status)
select building;
foreach (var b in q)
Console.WriteLine ("{0}: {1}", b.Name, b.Status);
}
produce i risultati attesi:
one: open
two: closed
four: open
five: closed
Questo programma confronta una rappresentazione di stringa enum e produce lo stesso risultato:
public class Building
{
public enum StatusType
{
open,
closed,
weird,
};
public string Name { get; set; }
public string Status { get; set; }
}
public static List <Building> buildingList = new List<Building>()
{
new Building() { Name = "one", Status = "open" },
new Building() { Name = "two", Status = "closed" },
new Building() { Name = "three", Status = "weird" },
new Building() { Name = "four", Status = "open" },
new Building() { Name = "five", Status = "closed" },
new Building() { Name = "six", Status = "weird" },
};
static void Main (string [] args)
{
var statusList = new List<Building.StatusType>() { Building.StatusType.open, Building.StatusType.closed };
var statusStringList = statusList.ConvertAll <string> (st => st.ToString());
var q = from building in buildingList
where statusStringList.Contains (building.Status)
select building;
foreach (var b in q)
Console.WriteLine ("{0}: {1}", b.Name, b.Status);
Console.ReadKey();
}
Ho creato questo metodo estensione convertire uno IEnumerable in un altro, ma non sono sicuro di quanto sia efficiente; potrebbe semplicemente creare una lista dietro le quinte.
public static IEnumerable <TResult> ConvertEach (IEnumerable <TSource> sources, Func <TSource,TResult> convert)
{
foreach (TSource source in sources)
yield return convert (source);
}
Quindi è possibile modificare la clausola dove:
where statusList.ConvertEach <string> (status => status.GetCharValue()).
Contains (v.Status)
e saltare la creazione del List<string>
con ConvertAll()
all'inizio.
Bello. Continuo a chiedermi perché in Terra Linq non fornisca un metodo 'Contains()', e poi mi rendo conto che si suppone che sia "Qualsiasi()" invece. +1 – Nolonar