We will implement two classes—FormationPattern and FormationManager:

1. Create the FormationPattern pseudo-abstract class:

using UnityEngine; 
using System.Collections; 
using System.Collections.Generic; 
 
public class FormationPattern: MonoBehaviour 
{ 
    public int numOfSlots; 
    public GameObject leader; 
} 

2. Implement the Start function:

void Start() 
{ 
    if (leader == null) 
        leader = transform.gameObject; 
} 

3. Define the function for getting the position for a given slot:

public virtual Vector3 GetSlotLocation(int slotIndex) 
{ 
    return Vector3.zero; 
} 

4. Define the function for retrieving, if a given number of slots is supported by the formation:

public bool SupportsSlots(int slotCount) 
{ 
    return slotCount <= numOfSlots; 
}

5. Implement the function for setting an offset in the locations, if necessary:

public virtual Location GetDriftOffset(List<SlotAssignment> slotAssignments) 
{ 
    Location location = new Location();
    location.position = leader.transform.position; 
    location.rotation = leader.transform.rotation; 
    return location; 
} 

6. Create the class for managing the formation:

using UnityEngine; 
using System.Collections; 
using System.Collections.Generic; 
 
public class FormationManager : MonoBehaviour 
{ 
    public FormationPattern pattern; 
    private List<SlotAssignment> slotAssignments; 
    private Location driftOffset; 
} 

7. Implement the Awake function:

void Awake() 
{ 
    slotAssignments = new List<SlotAssignment>(); 
} 

8. Define the function for updating the slot assignments given the list's order:

public void UpdateSlotAssignments() 
{ 
    for (int i = 0; i < slotAssignments.Count; i++) 
    { 
        slotAssignments[i].slotIndex = i; 
    } 
    driftOffset = pattern.GetDriftOffset(slotAssignments); 
}

9. Implement the function for adding a character to the formation:

public bool AddCharacter(GameObject character) 
{ 
    int occupiedSlots = slotAssignments.Count; 
    if (!pattern.SupportsSlots(occupiedSlots + 1)) 
        return false; 
    SlotAssignment sa = new SlotAssignment(); 
    sa.character = character; 
    slotAssignments.Add(sa); 
    UpdateSlotAssignments(); 
    return true; 
} 

10. Implement the function for removing a character in the formation:

public void RemoveCharacter(GameObject agent) 
{ 
    int index = slotAssignments.FindIndex(x => x.character.Equals(agent)); 
    slotAssignments.RemoveAt(index); 
    UpdateSlotAssignments(); 
} 

11. Implement the function for updating the slots:

public void UpdateSlots() 
{ 
    GameObject leader = pattern.leader; 
    Vector3 anchor = leader.transform.position; 
    Vector3 slotPos; 
    Quaternion rotation; 
    rotation = leader.transform.rotation; 
    foreach (SlotAssignment sa in slotAssignments) 
    { 
        // next step 
    } 
} 

12. Finally, implement the foreach loop:

Vector3 relPos; 
slotPos = pattern.GetSlotLocation(sa.slotIndex); 
relPos = anchor; 
relPos += leader.transform.TransformDirection(slotPos); 
Location charDrift = new Location(relPos, rotation); 
Character character = sa.character.GetComponent<Character>(); 
character.SetTarget(charDrift);