[something]Set class - why LINQ extension methods are not available

[adam.krug]

Hi all,

Last time I needed to extract the first element of ConnectorSet class, which implements IEnumerable interface. Thus I expected I could use LINQ extension method like:

myConnectorSet.FirstOrDefault()

But it's not available, why is that?

PS1: I used "using System.Linq"

PS2: I managed to get the first element with foreach loop, I'm only asking because I want to understand why LINQ methods are not available for *Set classes in Revit API

[jeremytammik]

The generic .NET LINQ methods require specific interfaces, e.g., IEnumerable.

The old-fashioned Revit API *Set implementation probably do not implement the required interfaces.

They are gradually being phased out and replaced by generic .NET collections anyway (and for that reason, among others).

Cheers,

Jeremy

[BobbyC.Jones · Accepted solution]

Because .FirstOrDefault() is an extension of IEnumerable<T>, not IEnumerable.  There are a number of options to get the first element out of the ConnectorSet, the easiest on my eyes is something like this:

var myFirstConnector = myConnectorSet.Cast<Connector>().FirstOrDefault();