Question

I want to make a collection that stores groups of users. A user can be a member of multiple groups, groups can be nested, a selection of groups should return a distinct IEnumerable<user> .

I could write this from scratch of course using the standard List<T>,Dictionary<T,U> etc collections, but is there a built-in collection that already exposes a lot of this behaviour?

Thanks!

Answer 1

I would do something like this:

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        List<User> users = new List<User>
        {
            // use a List<T> to hold the users themselves
        };
    }
}

class Group
{
    public Group NestedGroup { get; set; }
}

class User
{
    // Store the groups in a HashSet<T> to keep
    // a distinct list.
    HashSet<Group> groups;

    public IEnumerable<Group> Groups
    {
        get { return groups; }
    }
}

Using a List<T> to hold the users themselves should be fine. Notice that the Groups property of the User type is exposed as an IEnumerable<Group> but is implemented internally as a HashSet<Group> to allow you to keep a distinct list as you wanted.