Override Dictionary.Add

Question

Necesito saber cómo anular el Add-method de cierto Diccionario en cierta clase estática. ¿Alguna sugerencia?

si importa, el diccionario tiene el siguiente aspecto:

public static Dictionary<MyEnum,MyArray[]> 

¿Alguna sugerencia?

Answer 1

No puede anular el método Add de Dictionary<,> ya que no es virtual. Puede ocultarlo agregando un método con el mismo nombre/firma en la clase derivada, pero ocultar no es lo mismo que anular. Si alguien lanza a la clase base, seguirá llamando al Add incorrecto.

La forma correcta de hacerlo es crear su propia clase que implementa IDictionary<,> (la interfaz) pero tiene una (la clase) Dictionary<,> en lugar de estar un Dictionary<,>.

class MyDictionary<TKey,TValue>:IDictionary<TKey,TValue> 
{ 
    private Dictionary<TKey,TValue> backingDictionary; 

    //Implement the interface here 
    //Delegating most of the logic to your backingDictionary 
    ... 
} 

Answer 2

En realidad es más simple utilizar la palabra clave "nueva". Hago esto a menudo cuando mis objetos contienen su propio valor ID único.

// Warning Air Code - Subject to bonehead mistakes 

internal class SomeDict : Dictionary<myKeyType, myObjectType> 
{ 
    public new void Add(myKeyType key, myObjectType value) 
    { 
     this.Add(value); 
    } 

    internal void Add(myObjectType value) 
    { 
     base.Add(value.Id, value); 
    } 

} 

Answer 3

Fui con la solución de CodesInChaos. Dado que hay un poco de sobrecarga involucrado en la implementación de IDictionary<TKey, TValue>, aquí hay una implementación virtual para el consumo general. Incluyo algunos comentarios y un ejemplo a continuación para la lectura opcional. Avíseme si debería arreglar o mejorar algo. No he hecho muchas pruebas, pero parece funcionar para anular el método de agregar.

using System.Collections; 
using System.Collections.Generic; 

/// <summary> 
/// Represents a collection of keys and values. This is an abstract base-class wrapping a <see cref="T:System.Collections.Generic.Dictionary`2"/> with 
/// virtual method that can be overridden. This class can be used to override the default functionality of <see cref="T:System.Collections.Generic.Dictionary`2"/>. 
/// </summary> 
/// <typeparam name="TKey">The type of the keys in the dictionary.</typeparam> 
/// <typeparam name="TValue">The type of the values in the dictionary.</typeparam> 
public class VirtualDictionary<TKey, TValue> : IDictionary<TKey, TValue> 
{ 
    protected IDictionary<TKey, TValue> wrappedDictionary; 

    /// <summary> 
    /// Initializes a new instance of the <see cref="VirtualDictionary{TKey,TValue}"/> class that is empty, has the default initial capacity, and uses the default equality comparer for the key type. 
    /// </summary> 
    public VirtualDictionary() 
    { 
     wrappedDictionary = new Dictionary<TKey, TValue>(); 
    } 

    /// <summary> 
    /// Initializes a new instance of the <see cref="VirtualDictionary{TKey,TValue}"/> class that is empty, has the specified initial capacity, and uses the default equality comparer for the key type. 
    /// </summary> 
    /// <param name="capacity">The initial number of elements that the <see cref="T:System.Collections.Generic.VirtualDictionary`2"/> can contain.</param><exception cref="T:System.ArgumentOutOfRangeException"><paramref name="capacity"/> is less than 0.</exception> 
    public VirtualDictionary(int capacity) 
    { 
     wrappedDictionary = new Dictionary<TKey, TValue>(capacity); 
    } 

    /// <summary> 
    /// Initializes a new instance of the <see cref="VirtualDictionary{TKey,TValue}"/> class that is empty, has the default initial capacity, and uses the specified <see cref="T:System.Collections.Generic.IEqualityComparer`1"/>. 
    /// </summary> 
    /// <param name="comparer">The <see cref="T:System.Collections.Generic.IEqualityComparer`1"/> implementation to use when comparing keys, or null to use the default <see cref="T:System.Collections.Generic.EqualityComparer`1"/> for the type of the key.</param> 
    public VirtualDictionary(IEqualityComparer<TKey> comparer) 
    { 
     wrappedDictionary = new Dictionary<TKey, TValue>(comparer); 
    } 

    /// <summary> 
    /// Initializes a new instance of the <see cref="VirtualDictionary{TKey,TValue}"/> class that is empty, has the specified initial capacity, and uses the specified <see cref="T:System.Collections.Generic.IEqualityComparer`1"/>. 
    /// </summary> 
    /// <param name="capacity">The initial number of elements that the <see cref="VirtualDictionary{TKey,TValue}"/> can contain.</param><param name="comparer">The <see cref="T:System.Collections.Generic.IEqualityComparer`1"/> implementation to use when comparing keys, or null to use the default <see cref="T:System.Collections.Generic.EqualityComparer`1"/> for the type of the key.</param><exception cref="T:System.ArgumentOutOfRangeException"><paramref name="capacity"/> is less than 0.</exception> 
    public VirtualDictionary(int capacity, IEqualityComparer<TKey> comparer) 
    { 
     wrappedDictionary = new Dictionary<TKey, TValue>(capacity, comparer); 
    } 

    /// <summary> 
    /// Initializes a new instance of the <see cref="VirtualDictionary{TKey,TValue}"/> class that contains elements copied from the specified <see cref="T:System.Collections.Generic.IDictionary`2"/> and uses the default equality comparer for the key type. 
    /// </summary> 
    /// <param name="dictionary">The <see cref="T:System.Collections.Generic.IDictionary`2"/> whose elements are copied to the new <see cref="VirtualDictionary{TKey,TValue}"/>.</param><exception cref="T:System.ArgumentNullException"><paramref name="dictionary"/> is null.</exception><exception cref="T:System.ArgumentException"><paramref name="dictionary"/> contains one or more duplicate keys.</exception> 
    public VirtualDictionary(IDictionary<TKey, TValue> dictionary) 
    { 
     wrappedDictionary = new Dictionary<TKey, TValue>(dictionary); 
    } 

    /// <summary> 
    /// Initializes a new instance of the <see cref="VirtualDictionary{TKey,TValue}"/> class that contains elements copied from the specified <see cref="T:System.Collections.Generic.IDictionary`2"/> and uses the specified <see cref="T:System.Collections.Generic.IEqualityComparer`1"/>. 
    /// </summary> 
    /// <param name="dictionary">The <see cref="T:System.Collections.Generic.IDictionary`2"/> whose elements are copied to the new <see cref="VirtualDictionary{TKey,TValue}"/>.</param><param name="comparer">The <see cref="T:System.Collections.Generic.IEqualityComparer`1"/> implementation to use when comparing keys, or null to use the default <see cref="T:System.Collections.Generic.EqualityComparer`1"/> for the type of the key.</param><exception cref="T:System.ArgumentNullException"><paramref name="dictionary"/> is null.</exception><exception cref="T:System.ArgumentException"><paramref name="dictionary"/> contains one or more duplicate keys.</exception> 
    public VirtualDictionary(IDictionary<TKey, TValue> dictionary, IEqualityComparer<TKey> comparer) 
    { 
     wrappedDictionary = new Dictionary<TKey, TValue>(dictionary, comparer); 
    } 

    /// <summary> 
    /// Adds an element with the provided key and value to the <see cref="T:System.Collections.Generic.IDictionary`2"/>. 
    /// </summary> 
    /// <param name="key">The object to use as the key of the element to add.</param><param name="value">The object to use as the value of the element to add.</param><exception cref="T:System.ArgumentNullException"><paramref name="key"/> is null.</exception><exception cref="T:System.ArgumentException">An element with the same key already exists in the <see cref="T:System.Collections.Generic.IDictionary`2"/>.</exception><exception cref="T:System.NotSupportedException">The <see cref="T:System.Collections.Generic.IDictionary`2"/> is read-only.</exception> 
    public virtual void Add(TKey key, TValue value) 
    { 
     wrappedDictionary.Add(key, value); 
    } 

    /// <summary> 
    /// Determines whether the <see cref="T:System.Collections.Generic.IDictionary`2"/> contains an element with the specified key. 
    /// </summary> 
    /// <returns> 
    /// true if the <see cref="T:System.Collections.Generic.IDictionary`2"/> contains an element with the key; otherwise, false. 
    /// </returns> 
    /// <param name="key">The key to locate in the <see cref="T:System.Collections.Generic.IDictionary`2"/>.</param><exception cref="T:System.ArgumentNullException"><paramref name="key"/> is null.</exception> 
    public virtual bool ContainsKey(TKey key) 
    { 
     return wrappedDictionary.ContainsKey(key); 
    } 

    /// <summary> 
    /// Gets an <see cref="T:System.Collections.Generic.ICollection`1"/> containing the keys of the <see cref="T:System.Collections.Generic.IDictionary`2"/>. 
    /// </summary> 
    /// <returns> 
    /// An <see cref="T:System.Collections.Generic.ICollection`1"/> containing the keys of the object that implements <see cref="T:System.Collections.Generic.IDictionary`2"/>. 
    /// </returns> 
    public virtual ICollection<TKey> Keys 
    { 
     get 
     { 
      return wrappedDictionary.Keys; 
     } 
    } 

    /// <summary> 
    /// Removes the element with the specified key from the <see cref="T:System.Collections.Generic.IDictionary`2"/>. 
    /// </summary> 
    /// <returns> 
    /// true if the element is successfully removed; otherwise, false. This method also returns false if <paramref name="key"/> was not found in the original <see cref="T:System.Collections.Generic.IDictionary`2"/>. 
    /// </returns> 
    /// <param name="key">The key of the element to remove.</param><exception cref="T:System.ArgumentNullException"><paramref name="key"/> is null.</exception><exception cref="T:System.NotSupportedException">The <see cref="T:System.Collections.Generic.IDictionary`2"/> is read-only.</exception> 
    public virtual bool Remove(TKey key) 
    { 
     return wrappedDictionary.Remove(key); 
    } 

    /// <summary> 
    /// Gets the value associated with the specified key. 
    /// </summary> 
    /// <returns> 
    /// true if the object that implements <see cref="T:System.Collections.Generic.IDictionary`2"/> contains an element with the specified key; otherwise, false. 
    /// </returns> 
    /// <param name="key">The key whose value to get.</param><param name="value">When this method returns, the value associated with the specified key, if the key is found; otherwise, the default value for the type of the <paramref name="value"/> parameter. This parameter is passed uninitialized.</param><exception cref="T:System.ArgumentNullException"><paramref name="key"/> is null.</exception> 
    public virtual bool TryGetValue(TKey key, out TValue value) 
    { 
     return wrappedDictionary.TryGetValue(key, out value); 
    } 

    /// <summary> 
    /// Gets an <see cref="T:System.Collections.Generic.ICollection`1"/> containing the values in the <see cref="T:System.Collections.Generic.IDictionary`2"/>. 
    /// </summary> 
    /// <returns> 
    /// An <see cref="T:System.Collections.Generic.ICollection`1"/> containing the values in the object that implements <see cref="T:System.Collections.Generic.IDictionary`2"/>. 
    /// </returns> 
    public virtual ICollection<TValue> Values 
    { 
     get 
     { 
      return wrappedDictionary.Values; 
     } 
    } 

    /// <summary> 
    /// Gets or sets the element with the specified key. 
    /// </summary> 
    /// <returns> 
    /// The element with the specified key. 
    /// </returns> 
    /// <param name="key">The key of the element to get or set.</param><exception cref="T:System.ArgumentNullException"><paramref name="key"/> is null.</exception><exception cref="T:System.Collections.Generic.KeyNotFoundException">The property is retrieved and <paramref name="key"/> is not found.</exception><exception cref="T:System.NotSupportedException">The property is set and the <see cref="T:System.Collections.Generic.IDictionary`2"/> is read-only.</exception> 
    public virtual TValue this[TKey key] 
    { 
     get 
     { 
      return wrappedDictionary[key]; 
     } 
     set 
     { 
      wrappedDictionary[key] = value; 
     } 
    } 

    /// <summary> 
    /// Adds an item to the <see cref="T:System.Collections.Generic.ICollection`1"/>. 
    /// </summary> 
    /// <param name="item">The object to add to the <see cref="T:System.Collections.Generic.ICollection`1"/>.</param><exception cref="T:System.NotSupportedException">The <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only.</exception> 
    public virtual void Add(KeyValuePair<TKey, TValue> item) 
    { 
     wrappedDictionary.Add(item); 
    } 

    /// <summary> 
    /// Removes all items from the <see cref="T:System.Collections.Generic.ICollection`1"/>. 
    /// </summary> 
    /// <exception cref="T:System.NotSupportedException">The <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only. </exception> 
    public virtual void Clear() 
    { 
     wrappedDictionary.Clear(); 
    } 

    /// <summary> 
    /// Determines whether the <see cref="T:System.Collections.Generic.ICollection`1"/> contains a specific value. 
    /// </summary> 
    /// <returns> 
    /// true if <paramref name="item"/> is found in the <see cref="T:System.Collections.Generic.ICollection`1"/>; otherwise, false. 
    /// </returns> 
    /// <param name="item">The object to locate in the <see cref="T:System.Collections.Generic.ICollection`1"/>.</param> 
    public virtual bool Contains(KeyValuePair<TKey, TValue> item) 
    { 
     return wrappedDictionary.Contains(item); 
    } 

    /// <summary> 
    /// Copies the elements of the <see cref="T:System.Collections.Generic.ICollection`1"/> to an <see cref="T:System.Array"/>, starting at a particular <see cref="T:System.Array"/> index. 
    /// </summary> 
    /// <param name="array">The one-dimensional <see cref="T:System.Array"/> that is the destination of the elements copied from <see cref="T:System.Collections.Generic.ICollection`1"/>. The <see cref="T:System.Array"/> must have zero-based indexing.</param><param name="arrayIndex">The zero-based index in <paramref name="array"/> at which copying begins.</param><exception cref="T:System.ArgumentNullException"><paramref name="array"/> is null.</exception><exception cref="T:System.ArgumentOutOfRangeException"><paramref name="arrayIndex"/> is less than 0.</exception><exception cref="T:System.ArgumentException">The number of elements in the source <see cref="T:System.Collections.Generic.ICollection`1"/> is greater than the available space from <paramref name="arrayIndex"/> to the end of the destination <paramref name="array"/>.</exception> 
    public virtual void CopyTo(KeyValuePair<TKey, TValue>[] array, int arrayIndex) 
    { 
     wrappedDictionary.CopyTo(array, arrayIndex); 
    } 

    /// <summary> 
    /// Gets the number of elements contained in the <see cref="T:System.Collections.Generic.ICollection`1"/>. 
    /// </summary> 
    /// <returns> 
    /// The number of elements contained in the <see cref="T:System.Collections.Generic.ICollection`1"/>. 
    /// </returns> 
    public virtual int Count 
    { 
     get 
     { 
      return wrappedDictionary.Count; 
     } 
    } 

    /// <summary> 
    /// Gets a value indicating whether the <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only. 
    /// </summary> 
    /// <returns> 
    /// true if the <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only; otherwise, false. 
    /// </returns> 
    public virtual bool IsReadOnly 
    { 
     get { return wrappedDictionary.IsReadOnly; } 
    } 

    /// <summary> 
    /// Removes the first occurrence of a specific object from the <see cref="T:System.Collections.Generic.ICollection`1"/>. 
    /// </summary> 
    /// <returns> 
    /// true if <paramref name="item"/> was successfully removed from the <see cref="T:System.Collections.Generic.ICollection`1"/>; otherwise, false. This method also returns false if <paramref name="item"/> is not found in the original <see cref="T:System.Collections.Generic.ICollection`1"/>. 
    /// </returns> 
    /// <param name="item">The object to remove from the <see cref="T:System.Collections.Generic.ICollection`1"/>.</param><exception cref="T:System.NotSupportedException">The <see cref="T:System.Collections.Generic.ICollection`1"/> is read-only.</exception> 
    public virtual bool Remove(KeyValuePair<TKey, TValue> item) 
    { 
     return wrappedDictionary.Remove(item); 
    } 

    /// <summary> 
    /// Returns an enumerator that iterates through the collection. 
    /// </summary> 
    /// <returns> 
    /// A <see cref="T:System.Collections.Generic.IEnumerator`1"/> that can be used to iterate through the collection. 
    /// </returns> 
    /// <filterpriority>1</filterpriority> 
    public virtual IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator() 
    { 
     return wrappedDictionary.GetEnumerator(); 
    } 

    /// <summary> 
    /// Returns an enumerator that iterates through a collection. 
    /// </summary> 
    /// <returns> 
    /// An <see cref="T:System.Collections.IEnumerator"/> object that can be used to iterate through the collection. 
    /// </returns> 
    /// <filterpriority>2</filterpriority> 
    IEnumerator IEnumerable.GetEnumerator() 
    { 
     return GetEnumerator(); 
    } 
} 

Mi caso de uso iba a ser capaz de ejecutar el mismo código para manipular un DataTable y un resultado kendo fuente de datos que es IDictionary. Así que envolví la DataTable con mi IDictionary personalizado, de modo que las actualizaciones de IDictionary se realizaron en DataRow. Tal vez alguien lo encuentre útil y debería servir como ejemplo de implementación.

public class DataRowDictionaryWrapper : VirtualDictionary<string, object> 
{ 
    private DataRow row; 

    public DataRowDictionaryWrapper(DataRow row) 
    { 
     this.row = row; 
     this.wrappedDictionary = row.Table.Columns.Cast<DataColumn>().ToDictionary(key => key.ColumnName, c => row[c]); 
    } 

    public override void Add(string key, object value) 
    { 
     DataColumn col = row.Table.Columns[key]; 
     if (col == null) 
     { 
      col = new DataColumn(key); 
      row.Table.Columns.Add(col); 
     } 
     row[col] = value; 

     base[key] = value; 
    } 
} 

public class DataTableDictionaryWrapper : IEnumerable<IDictionary<string, object>> 
{ 
    private DataTable dt; 

    public DataTableDictionaryWrapper(DataTable dt) 
    { 
     this.dt = dt; 
    } 

    public IEnumerator<IDictionary<string, object>> GetEnumerator() 
    { 
     foreach (DataRow row in dt.Rows) 
     { 
      yield return new DataRowDictionaryWrapper(row); 
     } 
    } 

    System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() 
    { 
     return this.GetEnumerator(); 
    } 
} 

Answer 4

Otro "rápido y sucio" Fix

Si es necesario agregar algo de lógica adicional para el método Add, usted puede crear su propio método, con una firma ligeramente diferente, y el uso que en su código .

public class MyOwnDictionary<TKey, TValue>: Dictionary<TKey, TValue> 
{ 
    public void AddPlus(TKey key, TValue value) 
    { 
     //some custom logic here 

     base.Add(key,value); 
    } 
} 

(pero esto puede dar lugar a dificultades de mantenimiento)