DictionaryBase Class

The DictionaryBase class provides an abstract base class for a strongly typed collection of key/value pairs.

Assembly: System.Collections.dll

Syntax

public abstract class DictionaryBase : ICollection, IDictionary, IEnumerable, ISerializable, IDeserializationCallback

Members

Constructors

Signature	Access	Summary
`protected DictionaryBase()`	protected	Initializes a new instance of the `DictionaryBase` class.

Properties

Name	Signature	Access	Summary
Dictionary	`protected IDictionary Dictionary { get; }`	protected	Gets the underlying dictionary that stores the key/value pairs.
IsReadOnly	`public bool IsReadOnly { get; }`	public	Gets a value indicating whether the `DictionaryBase` is read-only.
Keys	`public ICollection Keys { get; }`	public	Gets an containing the keys of the `DictionaryBase`.
Values	`public ICollection Values { get; }`	public	Gets an containing the values of the `DictionaryBase`.

Methods

Name	Signature	Access	Summary
Add	`public void Add(object key, object value)`	public	Adds an element with the specified key and value into the `DictionaryBase`.
Clear	`public void Clear()`	public	Removes all elements from the `DictionaryBase`.
Contains	`public bool Contains(object key)`	public	Determines whether the `DictionaryBase` contains a specific key.
GetEnumerator	`public IDictionaryEnumerator GetEnumerator()`	public	Returns an enumerator that iterates through the `DictionaryBase`.
Remove	`public void Remove(object key)`	public	Removes the element with the specified key from the `DictionaryBase`.
OnClear	`protected virtual void OnClear()`	protected	Raises the `Clear` event.
OnInsert	`protected virtual void OnInsert(object key, object value)`	protected	Raises the `Insert` event.
OnRemove	`protected virtual void OnRemove(object key, object value)`	protected	Raises the `Remove` event.
OnSet	`protected virtual void OnSet(object key, object oldValue, object newValue)`	protected	Raises the `Set` event.

Example

The following example demonstrates how to derive a custom dictionary from DictionaryBase that enforces string keys and integer values.

using System;
using System.Collections;

public class StringIntDictionary : DictionaryBase
{
    public int this[string key]
    {
        get { return (int)Dictionary[key]; }
        set { Dictionary[key] = value; }
    }

    public void Add(string key, int value)
    {
        OnValidate(key, value);
        Dictionary.Add(key, value);
    }

    public bool Contains(string key)
    {
        return Dictionary.Contains(key);
    }

    public void Remove(string key)
    {
        Dictionary.Remove(key);
    }

    protected override void OnValidate(object key, object value)
    {
        if (key == null) throw new ArgumentNullException(nameof(key));
        if (!(key is string)) throw new ArgumentException("Key must be a string.");
        if (!(value is int)) throw new ArgumentException("Value must be an integer.");
    }

    public ICollection Keys => Dictionary.Keys;
    public ICollection Values => Dictionary.Values;
}

class Program
{
    static void Main()
    {
        var dict = new StringIntDictionary();
        dict.Add("Apples", 5);
        dict.Add("Oranges", 10);
        Console.WriteLine($"Apples: {dict["Apples"]}");
        Console.WriteLine($"Count: {dict.Count}");
    }
}