Selectors for MEF

LanguageSelector.cs

    [Export(typeof(LanguageSelector))]
    [PartCreationPolicy(CreationPolicy.Shared)]
    public class LanguageSelector : Selector<ILanguageProvider>
    {
        protected override string IdentityFor(ILanguageProvider import)
        {
            return import.Name;
        }

        protected override ILanguageProvider ImportFor(string identity)
        {
            foreach (var item in base.Options)
            {
                if (item.Name == identity)
                    return item;
            }
            return base.Options.First();
        }
    }

SelectionChangedEventArgs.cs

    /// <summary>
    /// Event arguments about a selection change.
    /// </summary>
    public class SelectionChangedEventArgs<TImport> : EventArgs
    {
        /// <summary>
        /// Gets the new selection.
        /// </summary>
        public TImport NewSelection
        {
            get;
            private set;
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="SelectionChangedEventArgs&lt;TImport&gt;"/> class.
        /// </summary>
        public SelectionChangedEventArgs(TImport newSelection)
        {
            NewSelection = newSelection;
        }
    }

Selector.cs

    /// <summary>
    /// Represens a selector.
    /// </summary>
    /// <typeparam name="TImport">The type of the import.</typeparam>
    public abstract class Selector<TImport>
    {
        /// <summary>
        /// Gets the options.
        /// </summary>
        [ImportMany(typeof(TImport))]
        public IEnumerable<TImport> Options
        {
            get;
            private set;
        }

        private TImport _selectedValue;
        /// <summary>
        /// Gets the selected value.
        /// </summary>
        public TImport SelectedValue
        {
            get
            {
                return SelectedValue;
            }
            private set
            {
                _selectedValue = value;
                var temp = SelectionChanged;
                if (temp != null)
                {
                    temp(this, new SelectionChangedEventArgs<TImport>(value));
                }
            }
        }

        /// <summary>
        /// Occurs when the selection is changed.
        /// </summary>
        public event EventHandler<SelectionChangedEventArgs<TImport>> SelectionChanged;

        /// <summary>
        /// Initializes a new instance of the <see cref="Selector&lt;TImport&gt;"/> class.
        /// </summary>
        public Selector()
        {
            Monoflector.CompositionServices.ComposeParts(this);
        }
        
        protected abstract string IdentityFor(TImport import); // We need this for saving settings later.
        protected abstract TImport ImportFor(string identity);
    }

SomewhereItsUsed.cs

    public class MustUseSelectedLanguage : IPartImportsSatisfiedNotification
    {
        [Import(typeof(LanguageSelector))]
        private LanguageSelector _selector;

        void IPartImportsSatisfiedNotification.OnImportsSatisfied()
        {
            _selector.SelectionChanged += new EventHandler<SelectionChangedEventArgs<ILanguageProvider>>(_selector_SelectionChanged);
            _theCombo.SelectedItem = _selector.SelectedValue;
            UpdateDissasemblers();
        }

        void _selector_SelectionChanged(object sender, SelectionChangedEventArgs<ILanguageProvider> e)
        {
            _theCombo.SelectedItem = _selector.SelectedValue;
            UpdateDissasemblers();
        }
    }