Implementing IList interface

c# generics collections ilist

41,621

Solution 1

Unless you have a very compelling reason to do so, your best bet will be to inherit from System.Collections.ObjectModel.Collection<T> since it has everything you need.

Please note that although implementors of IList<T> are not required to implement this[int] (indexer) to be O(1) (basically, constant-time access), it's strongly recommended you do so.

Solution 2

In addition to deriving from List<T>, you can facade List<T> and add more features to your facade class.

class MyCollection<T> : IList<T>
{
    private readonly IList<T> _list = new List<T>();

    #region Implementation of IEnumerable

    public IEnumerator<T> GetEnumerator()
    {
        return _list.GetEnumerator();
    }

    IEnumerator IEnumerable.GetEnumerator()
    {
        return GetEnumerator();
    }

    #endregion

    #region Implementation of ICollection<T>

    public void Add(T item)
    {
        _list.Add(item);
    }

    public void Clear()
    {
        _list.Clear();
    }

    public bool Contains(T item)
    {
        return _list.Contains(item);
    }

    public void CopyTo(T[] array, int arrayIndex)
    {
        _list.CopyTo(array, arrayIndex);
    }

    public bool Remove(T item)
    {
        return _list.Remove(item);
    }

    public int Count
    {
        get { return _list.Count; }
    }

    public bool IsReadOnly
    {
        get { return _list.IsReadOnly; }
    }

    #endregion

    #region Implementation of IList<T>

    public int IndexOf(T item)
    {
        return _list.IndexOf(item);
    }

    public void Insert(int index, T item)
    {
        _list.Insert(index, item);
    }

    public void RemoveAt(int index)
    {
        _list.RemoveAt(index);
    }

    public T this[int index]
    {
        get { return _list[index]; }
        set { _list[index] = value; }
    }

    #endregion

    #region Your Added Stuff

    // Add new features to your collection.

    #endregion
}

Solution 3

Visual Studio offers an automatic full working implementation of interfaces like IList<>.

You need only to write something like this code:

public class MyCollection<T> : IList<T>
{
    // This line is important. Without it the auto implementation creates only
    // methods with "NotImplemented" exceptions
    readonly IList<T> _list = new List<T>();
}

(while the line

readonly IList<T> _list = new List<T>();

is the important one!)

Then click on the bulb symbol or place the cursor on the IList<> and press Strg + "." You will become several implementations offered, like:

Solution 4

You can look at Mono project. There is available complete source codes, sou you can look how are some classes implemented. For example "System.Collections.Generics.List<T>".

Solution 5

In most cases you can simply use List<T> or derive from List<T>. If you derive from List<T> you will automatically get the implementation for Add and Remove.

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41,621

Ashish Ashu

Updated on July 09, 2022

Comments

Ashish Ashu almost 2 years

I am new to generics. I want to implement my own collection by deriving it from IList<T> interface.

Can you please provide me some link to a class that implements IList<T> interface or provide me a code that at least implements Add and Remove methods?
Ashish Ashu almost 15 years

after opening the home page of Mono project .. what should I download ??
Ashish Ashu almost 15 years

But in this case I can't bind my collection to DataGridView rather I have to expose the _list member in MyCollection.
Huntaz556 over 13 years

What are the drawbacks of doing this?
jp2code about 13 years

Sorry for the late response, but this one lost me @ IEnumerator<T> GetEnumerator returning GetEnumerator. This looks like a circular reference. How does this not cause a Stack Overflow Exception?
Thad about 11 years

Updated link to Mono class - github.com/mono/mono/blob/master/mcs/class/corlib/…
Jim over 10 years

@jp2code it's not an infinite loop. It is calling IEnumerator<T> GetEnumerator(). I have added a comment to the sample stating that.
gdbj over 9 years

Does IList<T> also implement IList? I thought it would, but I'm getting a compiler error. I guess List<T> does, but extending MyCollection so it can be cast as IList means also implementing that interface?
JasonG over 4 years

exactly what i needed. should be accepted answer as this is the correct way to do it.