Umbrella- collections++

As soon as the .NET framework allowed room for extension methods, this kind of thing was bound to happen. Umbrella is a 3rd party open source lib that adds extension methods and intuitive helper classes that make you wonder why they weren't there in the first place. The official codeplex site is here and the author's site is here. There are quite a few useful bits in this library for multiple purposes, but the real beauty comes through in its collections enhancements.

 

The downside of umbrella is its immaturity. To this date of september '08 I couldnt find any "official" documentation of the library per se (outside of blogs such as mine or Ayende's). Then again, maybe the unit tests speak for themselves. I sense that this project is a moving target, meaning that it is one of those open source projects in state of flux, which can make it a little hard to document.

Foreach on an IEnumerable

IEnumerable<string> items = new List<string> {"1", "2", "3", "4", "5"};
IList<string> actionItems = new List<string>();
//the old way
foreach (string s in items)
{
 actionItems.Add(s);
}
//the umbrella way
items.ForEach(actionItems.Add);

Indexed foreach actions:

IEnumerable<string> items = new List<string> {"1", "2", "3", "4", "5"};
string[] actionItems = new string[5];
//the old way
int i = 0;
foreach (string item in items)
{
 actionItems[i++] = item;
}
//the umbrella equivalent
items.ForEach((i, item) => actionItems[i] = item);

Pairing two lists of equal length together

IEnumerable<string> items = new List<string> {"1", "2", "3", "4", "5"};
IEnumerable<string> otherItems = new List<string> { "6", "7", "8", "9", "10" };
IEnumerable<Pair<string>> pairedItems = items.Pair(otherItems);
Assert.Equal(5, pairedItems.Count());
Assert.Equal("1", pairedItems.First().X);
Assert.Equal("6", pairedItems.First().Y);

Lazy-loading lists:

//lists that are declared but not consturcted until access-time
var list = new LazyList<int>(() => new List<int> { 1, 2, 3 });

Read-only lists:

//lists that cannot be added/removed from (without resorting to DataViews)
//ReadOnlyCollection is a part of the core .NET library, it takes an IList<T> as a constructor //argument
ReadOnlyCollection<string> readonly =  list.AsReadOnly();

Lists that convert between types
(This one is intricate and I am still studying it)

//Funcs is actually a generic collection of strategies for converting between types.
//the real magic behind conversion comes from
//System.ComponentModel.TypeDescriptor.GetConverter(type).ConvertFrom(value)
IList<string> adapter = new ListAdapter<int, string>(
               new List<int> { 1, 3, 4 },
               Funcs<string,int>.Convert,
               Funcs<int,string>.Convert);

           Assert.Equal(1, adapter.IndexOf("3"));

These are the pieces that I am using within my projects, but I am only scratching the surface. I suppose when it somes to collections, you can't have too much extensibility.

Download it, use it, or simply wait until these features are folded into the .NET lib in the next release ;)