Si la clé fait partie de la classe, utilisez KeyedCollection.
C'est un Dictionaryendroit où la clé est dérivée de l'objet.
Sous les couvertures, c'est le dictionnaire
. Pas besoin de répéter la clé dans le Keyet Value.
Pourquoi prendre une chance la clé n'est pas la même dans le Keyque le Value.
Pas besoin de dupliquer les mêmes informations en mémoire.
Classe KeyedCollection
Indexeur pour exposer la clé composite
using System.Collections.ObjectModel;
namespace IntIntKeyedCollection
{
class Program
{
static void Main(string[] args)
{
Int32Int32DateO iid1 = new Int32Int32DateO(0, 1, new DateTime(2007, 6, 1, 8, 30, 52));
Int32Int32DateO iid2 = new Int32Int32DateO(0, 1, new DateTime(2007, 6, 1, 8, 30, 52));
if (iid1 == iid2) Console.WriteLine("same");
if (iid1.Equals(iid2)) Console.WriteLine("equals");
// that are equal but not the same I don't override = so I have both features
Int32Int32DateCollection int32Int32DateCollection = new Int32Int32DateCollection();
// dont't have to repeat the key like Dictionary
int32Int32DateCollection.Add(new Int32Int32DateO(0, 0, new DateTime(2008, 5, 1, 8, 30, 52)));
int32Int32DateCollection.Add(new Int32Int32DateO(0, 1, new DateTime(2008, 6, 1, 8, 30, 52)));
int32Int32DateCollection.Add(iid1);
//this would thow a duplicate key error
//int32Int32DateCollection.Add(iid2);
//this would thow a duplicate key error
//int32Int32DateCollection.Add(new Int32Int32DateO(0, 1, new DateTime(2008, 6, 1, 8, 30, 52)));
Console.WriteLine("count");
Console.WriteLine(int32Int32DateCollection.Count.ToString());
// reference by ordinal postion (note the is not the long key)
Console.WriteLine("oridinal");
Console.WriteLine(int32Int32DateCollection[0].GetHashCode().ToString());
// reference by index
Console.WriteLine("index");
Console.WriteLine(int32Int32DateCollection[0, 1, new DateTime(2008, 6, 1, 8, 30, 52)].GetHashCode().ToString());
Console.WriteLine("foreach");
foreach (Int32Int32DateO iio in int32Int32DateCollection)
{
Console.WriteLine(string.Format("HashCode {0} Int1 {1} Int2 {2} DateTime {3}", iio.GetHashCode(), iio.Int1, iio.Int2, iio.Date1));
}
Console.WriteLine("sorted by date");
foreach (Int32Int32DateO iio in int32Int32DateCollection.OrderBy(x => x.Date1).ThenBy(x => x.Int1).ThenBy(x => x.Int2))
{
Console.WriteLine(string.Format("HashCode {0} Int1 {1} Int2 {2} DateTime {3}", iio.GetHashCode(), iio.Int1, iio.Int2, iio.Date1));
}
Console.ReadLine();
}
public class Int32Int32DateCollection : KeyedCollection<Int32Int32DateS, Int32Int32DateO>
{
// This parameterless constructor calls the base class constructor
// that specifies a dictionary threshold of 0, so that the internal
// dictionary is created as soon as an item is added to the
// collection.
//
public Int32Int32DateCollection() : base(null, 0) { }
// This is the only method that absolutely must be overridden,
// because without it the KeyedCollection cannot extract the
// keys from the items.
//
protected override Int32Int32DateS GetKeyForItem(Int32Int32DateO item)
{
// In this example, the key is the part number.
return item.Int32Int32Date;
}
// indexer
public Int32Int32DateO this[Int32 Int1, Int32 Int2, DateTime Date1]
{
get { return this[new Int32Int32DateS(Int1, Int2, Date1)]; }
}
}
public struct Int32Int32DateS
{ // required as KeyCollection Key must be a single item
// but you don't really need to interact with Int32Int32DateS directly
public readonly Int32 Int1, Int2;
public readonly DateTime Date1;
public Int32Int32DateS(Int32 int1, Int32 int2, DateTime date1)
{ this.Int1 = int1; this.Int2 = int2; this.Date1 = date1; }
}
public class Int32Int32DateO : Object
{
// implement other properties
public Int32Int32DateS Int32Int32Date { get; private set; }
public Int32 Int1 { get { return Int32Int32Date.Int1; } }
public Int32 Int2 { get { return Int32Int32Date.Int2; } }
public DateTime Date1 { get { return Int32Int32Date.Date1; } }
public override bool Equals(Object obj)
{
//Check for null and compare run-time types.
if (obj == null || !(obj is Int32Int32DateO)) return false;
Int32Int32DateO item = (Int32Int32DateO)obj;
return (this.Int32Int32Date.Int1 == item.Int32Int32Date.Int1 &&
this.Int32Int32Date.Int2 == item.Int32Int32Date.Int2 &&
this.Int32Int32Date.Date1 == item.Int32Int32Date.Date1);
}
public override int GetHashCode()
{
return (((Int64)Int32Int32Date.Int1 << 32) + Int32Int32Date.Int2).GetHashCode() ^ Int32Int32Date.GetHashCode();
}
public Int32Int32DateO(Int32 Int1, Int32 Int2, DateTime Date1)
{
Int32Int32DateS int32Int32Date = new Int32Int32DateS(Int1, Int2, Date1);
this.Int32Int32Date = int32Int32Date;
}
}
}
}
Quant à l'utilisation du type valeur fpr, la clé Microsoft le déconseille spécifiquement.
ValueType.GetHashCode
Tuple n'est techniquement pas un type valeur mais souffre du même symptôme (collisions de hachage) et n'est pas un bon candidat pour une clé.