RangedObservableCollection.workbook

packages	uti	id	title	platforms
id version RangedObservableCollection 1.0.0	com.xamarin.workbook	771a62d0-9764-4e3a-8642-1ae7ba5ad16a	RangedObservableCollection	Console

#r "System.Collections.ObjectModel.RangedObservableCollection"

RangedObservableCollection

A small extension to ObservableCollection that allows for multiple items to be added, removed or replaced in a single operation.

Like with all .NET libraries, we first need to add the using statement:

using System.Collections.ObjectModel;

Now that is done, we can instantiate the collection:

var collection = new RangedObservableCollection<int>();

Because this collection acts just like any ObservableCollection, there is not much to show… except for the awesome fact that adding a whole collection of items no longer meas that you get a whole lot of events. To show this, we are going to attach an event handler and print to the console each time there is an update:

collection.CollectionChanged += (s, e) =>
{
    Console.WriteLine ("Event raised!");
};

First we want to show the old way of doing things:

var itemsToAdd = new [] { 1, 2, 3, 4, 5 };
foreach (var item in itemsToAdd)
{
    collection.Add(item);
}

Whoah! We just broke our UI (or rather we did a whole lot of work that was not necessary). Instead, we should be doing this:

var itemsToAdd = new [] { 1, 2, 3, 4, 5 };
collection.AddRange(itemsToAdd);

Boom! Only a single event and our UI is happy! Not only can we add in bulk, we can remove a whole lot of items in one go too:

var itemsToRemove = new [] { 1, 2, 3, 4, 5 };
collection.RemoveRange(itemsToRemove);

Again, just a single event. Finally, we can replace all the items in the collection in a single action, without having to clear the collections first:

var itemsToAdd = new [] { 1, 2, 3, 4, 5 };
collection.ReplaceRange(itemsToAdd);

As you can see, just a single event. Now go forth and conquer!