Initialize a List<T> with values that are not null

Question

I'm looking for a way to initialize a variable of type List with a set of values (in C#). Yes, there is object initialization but that requires a new object for each value you want and I would rather avoid it.

Here's a sample:

class MyObject
{
  public string Name {get;set;}
}
List<MyObject> OldNames = new List<MyObject>(10);
List<MyObject> NewNames = new List<MyObject>(5);

This is fine and dandy but OldNames contains 10 null references to an object of type MyObject.

Using a list initializer I could do this:

List<MyObject> OldNames = new List<MyObject>{
  new MyObject(),
  new MyObject(),
  new MyObject(),
  etc.

That's kind of a pain as I have many list variables and various sizes to initialize (for exaample one variable is a list of 26 objects. Yes, I could write a function or maybe extension to do this initialization for me (in a loop where I provide the size) but again that's code I don't necessarily want to write.

I'm hoping there's some kind of lamdba or LINQ expression or something to initialize a list of objects to values instead of nulls.

Thanks!

Answer 1

Use the Enumerable.Range LINQ method to specify the number of iterations.

List<MyObject> NewNames = Enumerable.Range(1,5).Select(i => new MyObject()).ToList();

The number 1 here is arbitrary, as the indexer is not used in any way.

Answer 2

Just a quick musing... you can use Enumerable.Repeat... just not the way it's been done before. This would work:

var query = Enumerable.Repeat<Func<MyObject>>(() => new MyObject(), count)
                      .Select(x => x())
                      .ToList();

I'm not suggesting you should do this, but it's an interesting alternative to Enumerable.Range.