Does C# 7 have array/enumerable destructuring?

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It turns out not only tuples can be deconstructed but any type which has Deconstruct static (or extension) method with matching signature. Doing deconstruction correctly for IEnumerable is not trivial (see library suggested by David Arno in this answer), so let’s see how it works with simple IList instead (implementation is irrelevant, this one is for example and of course can be better/different):

public static class Extensions {
    public static void Deconstruct<T>(this IList<T> list, out T first, out IList<T> rest) {
        first = list.Count > 0 ? list[0] : default(T); // or throw
        rest = list.Skip(1).ToList();
    }

    public static void Deconstruct<T>(this IList<T> list, out T first, out T second, out IList<T> rest) {
        first = list.Count > 0 ? list[0] : default(T); // or throw
        second = list.Count > 1 ? list[1] : default(T); // or throw
        rest = list.Skip(2).ToList();
    }
}

Then (after adding relevant using statements if necessary) you can use exactly the syntax you want:

var list = new [] {1,2,3,4};
var (a,rest) = list;
var (b,c,rest2) = list;

Or you can chain deconstruction like this (because last returned value can itself be deconstructed):

 var (a, (b, (c, rest))) = list;

With last version, you can deconstruct to any number of items using single Deconstruct method (that one which returns first item and the rest).

For real usage for IEnumerables, I’d suggest to not reimplement the wheel and use David Arno’s library mentioned in this answer.

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