[API Proposal]: Random.NextArray function

[CypherPotato]

Background and motivation

The motivation for this issue is that I needed to perform a similar task, but I couldn't find any native way to do it. I wondered why there isn't something ready in the System.Random class, which already has helpers for generating random data, and I believe this suggestion makes sense.

API Proposal

The behavior is simple and straightforward. The following extension function does exactly what I am proposing.

public static T NextArray<T> ( this Random random, IReadOnlyList<T> items ) {
    return items [ random.Next ( 0, items.Count ) ];
}

Or within the Random class:

public static T NextArray<T> ( IReadOnlyList<T> items ) {
    return items [ this.Next ( 0, items.Count ) ];
}

In .NET 9 we could extend IReadOnlyList<T> to allow params in the parameter.

API Usage

string [] fruits = [ "Apple", "Mango", "Tomato", "Blueberry" ];
string randomFruit = Random.Shared.NextArray ( fruits );

Console.WriteLine ( randomFruit );

Alternative Designs

No response

Risks

Perhaps a risk would be trying to access an item after it has been removed and the Count has been reduced shortly after accessed. A lock would solve this, but we would have to change the input type, as IReadOnlyList<T> does not implement ICollection.SyncRoot.

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[huoyaoyuan]

The proposed name is confusing. NextArray means returning an array. The proposed functionality is to return one random element from an array-like.

In real-world usage, there are also usage that requires no duplications while randomly picking items. This is more complicated and can be helped by Random.Shuffle. On the other hand, items[random.Next(0, item.Count)] is too trivial.

[CypherPotato]

@huoyaoyuan NextItem maybe? I didn't thinked so much about the method name, but that's not the issue main objective. And, I disagree, it's not so trivial, I've come across some situations like choosing a welcome message from a list of pre-defined messages. Depending on how it is implemented, it leaves room for small errors which can break the code in runtime.

In the case of duplicates, it would only make sense if you were getting several random items from an array in series, not something momentary. If it's the first case and you need to filter results, NextArray may not be the best way to do it.

Also, we could allow an overload with IEnumerable<T> to allow a better filtering of the expected result.

[colejohnson66]

IEnumerable would not work because the size of the enumeration is unbounded. Randomly sampling it is impossible.

[KeterSCP]

This was previously proposed and rejected in #80651 (comment)