C#

Richard Deeming wrote:

And if two threads append an item at the same time, what order do you expect them to appear in?

void Foo() { ... }

MyContainingForm form = new MyContainingForm();
...
form.TheMethodYouWantToCall();

MyContainingForm.TheMethodYouWantToCall();

public static class Functional
{
    public static Func<TResult> Apply<TArg, TResult>(this Func<TArg, TResult> fn, TArg arg)
    {
        return () => fn(arg);
    }
}

public class Worker
{
    public Func<List<string>> DataSource { get; set; }

    public void Execute()
    {
        var data = DataSource();
        data.ForEach(x => Console.WriteLine(x));
    }
}

internal class Program
{
    static void Main(string[] args)
    {
        var repo = new Repo();
        var myClass = new Worker();
        
        myClass.DataSource = Functional.Apply(repo.GetData, 10);
        
        /*
         Or:
         
         Func<int, List<string>> fn = repo.GetData;
         myClass.DataSource = fn.Apply(10);
         */

        myClass.Execute();
        Console.ReadLine();
    }
}

// at top-level:
public static int defaultNumValue = 10;

public class Repo
{
    public List<string> GetData(int num = defaultNumValue)
    {
        var results = new List<string>();

        for (int x = 0; x < num; x++)
        {
            results.Add($"Result{x}");
        }

        return results;
    }
}