Reputation: 3442
I want to pass parameter in constructor into generic function with constraints. Is it possible to create instance of T
with parameters? Something like list.Add(new T(1));
namespace ConsoleApplication
{
class Program
{
static void Main(string[] args)
{
List<Base> list = new List<Base>();
AddElement<Quick>(list,5);
AddElement<Range>(list, 5);
Console.WriteLine(list.Count);
Console.ReadKey();
}
public static void AddElement<T>(List<Base> list, int number) where T : Base, new ()
{
for (int i = 0; i < number; i++)
{
//do not working
list.Add(new T(i));
}
}
}
public abstract class Base
{
}
public class Quick:Base
{
private int ID;
public Quick()
{
}
public Quick(int ID)
{
this.ID = ID;
}
}
public class Range : Base
{
private int ID;
public Range()
{
}
public Range(int ID)
{
this.ID = ID;
}
}
}
Upvotes: 2
Views: 98
Reputation: 109547
The usual way around this is to pass a factory method or Func<T>
to the method:
public static void AddElement<T>(List<Base> list, int number, Func<T> factory) where T : Base
{
for (int i = 0; i < number; i++)
{
list.Add(factory());
}
}
You can use that with your Quick
class like this:
var baseList = new List<Base>();
AddElement(baseList, 5, () => new Quick(1));
If you wanted to be able to pass the int
constructor argument inside AddElement<T>()
you can use a Func<int, T>
instead like so:
public static void AddElement<T>(List<Base> list, int number, Func<int, T> factory) where T : Base
{
for (int i = 0; i < number; i++)
{
list.Add(factory(i));
}
}
Then call it like so:
var baseList = new List<Base>();
AddElement(baseList, 5, x => new Quick(x));
Upvotes: 4