Query iterator entity has to use ref?

[adjourn]

Documentation contains the following examples:

world.Query(in query, (Entity entity) => {}); 
world.Query(in query, (Entity en, ref T1 t1.) => {});

But using entity like this gives me different errors:

world.Query(
  in query,
  (Entity entity) => {} // Cannot convert lambda expression to type 'ForEach' because the parameter types do not match the delegate parameter types
); 

world.Query(
  in query,
  (Entity en, ref T1 t1) => {} // Delegate 'ForEach' does not take 2 arguments
);

What's the deal here? Any ideas why it seems to act differently for me?

---

Using ref Entity entity gets rid of the error but then I'm running into other issues..

world.Query(in query, (ref Entity entity) => {
  button.Clicked += () => {
     Ui.Open(entity); // Cannot use ref, out, or in parameter 'entity' inside an anonymous method, lambda expression, query expression, or local function
  };
}); 

[metaphist]

It might help to see your query for world.Query(in query, (Entity entity) => {});

[adjourn]

@metaphist

struct Player { } // tag

struct Position {
  public Vector3 Vector3;
}

var query = new QueryDescription().WithAll<Player, Position>();

world.Query(
  in query,
  (Entity en) => {} // Cannot convert lambda expression to type 'ForEach' because the parameter types do not match the delegate parameter types
);
world.Query(
  in query,
  (Entity en, ref Player player) => {} // Delegate 'ForEach' does not take 2 arguments
);
world.Query(
  in query,
  (Entity en, ref Player player, ref Position position) => {} // Delegate 'ForEach' does not take 3 arguments
);

[adjourn]

I should add that it works without entity argument:

world.Query(
  in query,
  (ref Player player, ref Position position) => {
    // yee
  }
);

[metaphist]

Not sure, I've encountered the error before while tinkereing, but I think it had to do with some implementation error elsewhere in my files.

Try comparing your code to this version from the readme that I modified to query on Entity.

using Arch.Core;

// Components ( ignore the formatting, this saves space )
public struct Position { public float X, Y; };
public struct Velocity { public float Dx, Dy; };

public sealed class Game
{
    public static void Main(string[] args)
    {
        // Create a world and entities with position and velocity.
        var world = World.Create();
        for (var index = 0; index < 1000; index++)
            world.Create(new Position { X = 0, Y = 0 }, new Velocity { Dx = 1, Dy = 1 });

        // Query and modify entities ( There are also alternatives without lambdas ;) ) 
        var query = new QueryDescription().WithAll<Position, Velocity>(); // Targets entities with Position AND Velocity.
        world.Query(in query, (Entity en) =>
        {
            //pos.X += vel.Dx;
            //pos.Y += vel.Dy;
        });
    }
}

[adjourn]

@metaphist Thank you for stopping and trying to help - the cause was actually in the version.
So a tip to all future readers - if something is wrong, first try to update to latest version!