Combine Multiple Predicates

Question

Is there any way in c# .NET 2.0! to combine multiple Predicates?

Let\'s say I have the following code.

List names = new List

        

Answer 1

How about:

public static Predicate Or(params Predicate[] predicates)
{
    return delegate (T item)
    {
        foreach (Predicate predicate in predicates)
        {
            if (predicate(item))
            {
                return true;
            }
        }
        return false;
    };
}

And for completeness:

public static Predicate And(params Predicate[] predicates)
{
    return delegate (T item)
    {
        foreach (Predicate predicate in predicates)
        {
            if (!predicate(item))
            {
                return false;
            }
        }
        return true;
    };
}

Then call it with:

List filteredNames = names.FindAll(Helpers.Or(StartsWithE, StartsWithI));

Another alternative would be to use multicast delegates and then split them using GetInvocationList(), then do the same thing. Then you could do:

List filteredNames = names.FindAll(Helpers.Or(StartsWithE+StartsWithI));

I'm not a huge fan of the latter approach though - it feels like a bit of an abuse of multicasting.