Class does not implement Interface and code still compiles

Question

I need to create a custom collection that implements IBindingList in order to be able to bind it with a custom control from 3rd party. Another problem that I have is that I have to make that collection thread safe because I manually insert items from multiple threads simultaneously.

Anyways I am using a BindingList<T> as a field on my class in order to don't reinvent the wheel to much. So my class looks like:

class ThreadSaveBindingCollection<T> : IEnumerable<T>, IBindingList
{
    BindingList<T> collection;
    object _lock = new object();

    // constructors
    public ThreadSaveBindingCollection(IEnumerable<T> initialCollection)
    {
        if (initialCollection == null)
            collection = new BindingList<T>();
        else                            
            collection = new BindingList<T>(new List<T>(initialCollection));                                 
    }
    public ThreadSaveBindingCollection() : this(null)
    {            
    }   

    // Todo: Implement interfaces using collection to do the work    
}

Note I am missing to implement the interface IEnumerable and IBinding list. I am planning for the field collection to take care of that as it implements those interfaces as well. So I let visual studio implement the interface explicitly and replace the throw new NotImplementedException() with the field collection implementation and I end up with something like:

enter image description here

Now the question is

Why I cannot call the method AddIndex on the field collection if collection claims to implement IBindingList!?

enter image description here

I am not able to do the same thing for several of the methods

It looks like your second code block is missing. Can you make sure all of the relevant code is in your question? — Chris
– Chris, Commented Nov 23, 2012 at 16:38

Kent Boogaart · Accepted Answer · 2012-11-23 16:39:00Z

1

It's because it's an explicit implementation of the interface, rather than implicit. This means you must call it through the interface rather than the type itself. For example:

((IBindingList)collection).AddIndex(property);

See here for more information on explicit interface implementations.

answered Nov 23, 2012 at 16:39

Kent Boogaart

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Adam Houldsworth · Accepted Answer · 2012-11-23 16:38:28Z

1

It is implemented explicity by BindingList, you need to cast your reference of collection to IBindingList to use it:

(collection as IBindingList).AddIndex(property);

http://msdn.microsoft.com/en-us/library/ms132679.aspx

Comments

Tyler Lee · Accepted Answer · 2012-11-23 16:39:51Z

1

BindingList explicitly implements IBindingList, so you need to do

(collection as IBindingList).AddIndex(property);

answered Nov 23, 2012 at 16:39

Tyler Lee

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