Calling a string equivalent method

Question

Consider the following class:

public class AnimationManager : MonoBehaviour {
    public GameObject[] Enemies;

    void OnTriggerEnter2D (Collider2D o) {
        if (o.tag == "Player")
            foreach(GameObject Enemy in Enemies)
                //Eval(Enemy.transform.name + "Animation();");
    }

    void MacacoAnimation(){
        //...
    }
}

What I want is when the object collides with the player, the script executes a method equivalent to the name of the object concatenated with the string "Animation".

See where to enter the commented code:

Eval(Enemy.transform.name + "Animation();");

Here I would execute the method, but I don’t know how to do.

Answer 1

I advise doing this with delegated methods and not using string to set the method call. It looks like you are using an event to trigger events, only the wrong way.

But I’ll give you an answer because I might not be able to do it this way:

var nomeMetodo = Enemy.transform.name + "Animation";
var Metodo = this.GetType().GetMethod(nomeMetodo);
Metodo.Invoke(this, null);

Behold working in the ideone. And in the .NET Fiddle. Also put on the Github for future reference.

An optimization would be:

var Metodo = typeof(AnimationManager).GetMethod(nomeMetodo);

I don’t know if this totally solves what you need but it’s what came out without a bigger context.

Obviously if the string contain a name that cannot generate a valid method, will give exception.

Answer 2

In Unity, the way to execute a method from another script is as follows::

Objeto.GetComponent<NomeDaClasseDoScript>().NomeDoMetodo();

Or

Objeto.GetComponent("NomeDaClasseDoScript").NomeDoMetodo();

The second form has disadvantages in performance (because it needs to reflect in a sense similar to what @Maniero has described to you), but it works for what you want. So you can do it this way:

1. Create different scripts instead of different methods in a single script. Each script will have the name you are setting (in transform.name). And all of them will have the same method animation (of course, each doing what they have to do differently).

2. Execute the method as follows: Enemy.GetComponent(Enemy.transform.name).Animation();. Note that this can cause errors while running your game if the script with the name Enemy.transform.name not exist!

That said, I would like to mention that I understand what you want to do but I don’t understand exactly why you want to do this. You are centralizing control of the animation in a class called AnimationManager, when it could have left it to the class of each enemy (the enemy can also detect the collision and, alone, perform its animation). From the point of view of object orientation this is a very bad choice, because it creates an unnecessary coupling and will certainly hinder its future maintenance.