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March 14, 2008
EmptyIfNull
Another great use for the fact that C# extension methods work on null references is a method we call EmptyIfNull:
public static IEnumerable<T> EmptyIfNull<T>(this IEnumerable<T> seq)
{
return seq ?? Enumerable.Empty<T>();
}
This extension method simply returns the specified enumerable, unless it is null, in which case it returns an empty enumerable. It requires slightly less typing than using the null-coalescing operator.
For example, suppose the GetNames method normally returns a collection of strings, but could return null if there are none. Either of these statements will write each of the strings to the console:
(GetNames() ?? Enumerable.Empty<string>()).
ToList().ForEach(Console.WriteLine);
GetNames().EmptyIfNull().ToList().ForEach(Console.WriteLine);
I like the EmptyIfNull syntax better.
Posted by Ed Ball at March 14, 2008 11:07 AM
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