koobas.hobune.stream
How to obtain Subclasses of a class/type?
Say, I have a class called EnemyUnit and multiple subclasses of it called EnemyArcher, EnemyInfantry, etc.
I'm creating an AI for movement in a game and I want to have an EnemyArcher stay one space away from a player unit. The problem is how to check if the current iteration of EnemyUnit in a foreach loop [EnemyUnit enemy in enemyUnitList] is an EnemyArcher? All enemy units have the tag "Enemy" if that helps, but I doubt it.
Can GetComponent work? and if so, how? Thanks.
Assuming you have the class hierarchy something like this :
EnemyUnit (base class)
EnemyArcher
EnemyCaster
EnemyWarrior
Then you can do :
List<EnemyUnit> enemies;
// Fill the list
// Iterate the list
for (int i = 0; i < enemies.Length ; i++)
{
if (enemies[i] is EnemyArcher)
{
// Enemy is archer subclass
} else if (enemies[i] is EnemyCaster)
{
// Enemy is caster subclass
}
}
The is operator is a fundamental operator in OOP ;) However it's usually easier to directly use the as operator since both perform the same check, but the as operator also cast the reference into that type, if possible:
for (int i = 0; i < enemies.Length ; i++)
{
EnemyArcher archer = enemies[i] as EnemyArcher;
if (archer != null)
{
// Enemy is archer subclass
// use "archer" here
continue;
}
EnemyCaster caster = enemies[i] as EnemyCaster;
if (caster != null)
{
// Enemy is caster subclass
// use "caster" here
continue;
}
}
The as-cast does a type check and doesn't throw an exception if it fails but simply returns null. The advantage is that you have both in once: The type check and the cast which is usually necessary since you want to access something specific for this class.
Use polymorphism, way better and faster.
Your enemy class contains all basic info about enemy, sub classes just override the contents when needed.
public abstract class Enemy:MonoBehaviour{
public abstract void Move();
}
public class EnemyCaster:Enemy{
public override void Move(){print("EnemyCaster");}
}
public class EnemyArcher:Enemy{
public override void Move(){print("EnemyArcher");}
}
now you can create a collection of enemy and place those into it.
List<Enemy>list = new List<Enemy>();
foreach(Enemy enemy in list){
enemy.Move();
}
This will print the implementation in the sub class even though you have a collection of top class. This is polymorphism, one of the three big lines of OOP (encapsulation, inheritance, polymorphism).
