System.Windows.Forms.ListBindingHelper.GetList C# (CSharp) Méthode

        public static object GetList(object dataSource, string dataMember) {
            //
            // The purpose of this method is to find a list, given a 'data source' object and a
            // decription of some 'data member' property of that object which returns the list.
            //
            // - If the data source is not a list, we get the list by just querying for the
            //   current value of that property on the data source itself.
            //
            // - If the data source is a list, we have to first pick some item from that list,
            //   then query for the value of that property on the individual list item.
            //

            dataSource = GetList(dataSource);
            if (dataSource == null || dataSource is Type || String.IsNullOrEmpty(dataMember)) {
                return dataSource;
            }

            PropertyDescriptorCollection dsProps = ListBindingHelper.GetListItemProperties(dataSource);
            PropertyDescriptor dmProp = dsProps.Find(dataMember, true);
            if (dmProp == null) {
                throw new System.ArgumentException(SR.GetString(SR.DataSourceDataMemberPropNotFound, dataMember));
            }

            object currentItem;

            if (dataSource is ICurrencyManagerProvider) {
                // Data source is another BindingSource so ask for its current item
                CurrencyManager cm = (dataSource as ICurrencyManagerProvider).CurrencyManager;
                bool currentKnown = (cm != null && cm.Position >= 0 && cm.Position <= cm.Count - 1);
                currentItem = currentKnown ? cm.Current : null;
            }
            else if (dataSource is IEnumerable) {
                // Data source is an enumerable list, so walk to the first item
                currentItem = GetFirstItemByEnumerable(dataSource as IEnumerable);
            }
            else {
                // Data source is not a list, so just use the data source itself
                currentItem = dataSource;
            }

            // Query the data member property on the chosen object to get back the list
            return (currentItem == null) ? null : dmProp.GetValue(currentItem);
        }

        void ResetList()
        {
            if (!is_initialized)
            {
                return;
            }

            IList  l;
            object source = ListBindingHelper.GetList(datasource, datamember);

            //
            // If original source is null, then create a new object list
            // Otherwise, try to infer the list item type
            //

            if (datasource == null)
            {
                l = new BindingList <object>();
                //list_defaulted = true;
            }
            else if (source == null)
            {
                //Infer type based on datasource and datamember,
                // where datasource is an empty IEnumerable
                // and need to find out the datamember type

                Type property_type = ListBindingHelper.GetListItemProperties(datasource) [datamember].PropertyType;
                Type t             = typeof(BindingList <>).MakeGenericType(new Type [] { property_type });
                l = (IList)Activator.CreateInstance(t);
            }
            else if (source is IList)
            {
                l = (IList)source;
            }
            else if (source is IEnumerable)
            {
                IList new_list = GetListFromEnumerable((IEnumerable)source);
                l = new_list == null ? list : new_list;
            }
            else if (source is Type)
            {
                Type t = typeof(BindingList <>).MakeGenericType(new Type [] { (Type)source });
                l = (IList)Activator.CreateInstance(t);
            }
            else
            {
                Type t = typeof(BindingList <>).MakeGenericType(new Type[] { source.GetType() });
                l = (IList)Activator.CreateInstance(t);
                l.Add(source);
            }

            SetList(l);
        }