Passing a single item as IEnumerable<T>
Is there a common way to pass a single item of type T to a method which expects an IEnumerable<T> parameter? Language is C#, framework version 2.0.
Currently I am using a helper method (it's .Net 2.0, so I have a whole bunch of casting/projecting helper methods similar to LINQ), but this just seems silly:
public static class IEnumerableExt
{
// usage: IEnumerableExt.FromSingleItem(someObject);
public static IEnumerable<T> FromSingleItem<T>(T item)
{
yield return item;
}
}
Other way would of course be to create and populate a List<T> or an Array and pass it instead of IEnumerable<T> .
[Edit] As an extension method it might be named:
public static class IEnumerableExt
{
// usage: someObject.SingleItemAsEnumerable();
public static IEnumerable<T> SingleItemAsEnumerable<T>(this T item)
{
yield return item;
}
}
Am I missing something here?
[Edit2] We found someObject.Yield() (as @Peter suggested in the comments below) to be the best name for this extension method, mainly for brevity, so here it is along with the XML comment if anyone wants to grab it:
public static class IEnumerableExt
{
/// <summary>
/// Wraps this object instance into an IEnumerable<T>
/// consisting of a single item.
/// </summary>
/// <typeparam name="T"> Type of the object. </typeparam>
/// <param name="item"> The instance that will be wrapped. </param>
/// <returns> An IEnumerable<T> consisting of a single item. </returns>
public static IEnumerable<T> Yield<T>(this T item)
{
yield return item;
}
}
Your helper method is the cleanest way to do it, IMO. If you pass in a list or an array, then an unscrupulous piece of code could cast it and change the contents, leading to odd behaviour in some situations. You could use a read-only collection, but that's likely to involve even more wrapping. I think your solution is as neat as it gets.
Well, if the method expects an IEnumerable you've got to pass something that is a list, even if it contains one element only.
passing
new T[] { item }
as the argument should be enough I think
In C# 3.0 you can utilize the System.Linq.Enumerable class:
// using System.Linq
Enumerable.Repeat(item, 1);
This will create a new IEnumerable that only contains your item.
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