Weapon Decorator C#

Hi there, i'm trying to do a simple weapon decorator for a pistol. I understand how decorator works and how is the structure but i have some question about it.

i have my Component

Code (CSharp):

1. public class WeaponComponent : MonoBehaviour
2. {
3.     public Transform noseTransform;
4.  
5.     protected float shootDistance = 0;
6.     public virtual void Shoot()
7.     {}
8. }

then i have my Concrete Component

Code (CSharp):

1. public class PistolWeapon : WeaponComponent
2. {
3.     public PistolWeapon()
4.     {
5.         shootDistance = 30;
6.     }
7.  
8.     public override void Shoot ()
9.     {
10.         Debug.Log("Shooting Distance: "+shootDistance);
11.     }
12. }

My Decorator

Code (CSharp):

1. public abstract class WeaponDecorator : WeaponComponent
2. {
3. }

My Concrete Decorator

Code (CSharp):

1. public class SilencerDecorator : WeaponDecorator
2. {
3.     private WeaponComponent _wC;
4.  
5.     public SilencerDecorator(WeaponComponent wC)
6.     {
7.         _wC = wC;
8.         GameObject go = (GameObject)Instantiate(Resources.Load("Silencer"),_wC.noseTransform.position,Quaternion.identity);
9.         go.transform.parent = _wC.noseTransform;
10.     }
11.  
12.     public override void Shoot ()
13.     {
14.         base.Shoot ();
15.         shootDistance = 20;
16.         Debug.Log("Shotting with Silencer. Distance: "+shootDistance);
17.     }
18. }

And then i have my testing script

Code (CSharp):

1. public class Testing : MonoBehaviour {
2.  
3.     // Use this for initialization
4.     void Start ()
5.     {  
6.         GameObject go = (GameObject)Instantiate(Resources.Load("Pistol"));
7.         WeaponComponent pistol = go.GetComponent<PistolWeapon>();
8.         pistol.Shoot();
9.         pistol = new SilencerDecorator(pistol);
10.         pistol.Shoot();
11.  
12.     }
13. }

The output is what i expected.

Code (CSharp):

1. //First only the Pistol
2. Shooting Distance: 30
3. UnityEngine.Debug:Log(Object)
4. //Then the pistol with silencer
5. Shooting Distance: 20
6. UnityEngine.Debug:Log(Object)

But then i thought. What if i want to insert a Grip into the weapon that affect only a variable.
GripDecorator doesnt have to Shoot, but if i do a new GripDecorator and says pistol.Shoot() will shoot the Grip. I'm confused on that.

 

Aren't you getting some warning that a class deriving from MonoBehaviour should not be created with "new"?

 

your decorator isn't calling shoot on the actual weapon it decorates.

you have properties on the top class that are specific to a certain kind of weapon

your decorator should wrap another class, effect that class, and then call shoot on it

 

Like this (note this is just a example code, components of course should avoid constructors, and the wrapping of the weapon should be handled in Awake):

Code (csharp):

1.  
2. public abstract class Weapon
3. {
4.  
5.     public virtual void Shoot()
6.     {
7.         //override
8.     }
9.  
10. }
11.  
12. public class Pistol : Weapon
13. {
14.  
15.     public float Range = 30;
16.  
17.     public override void Shoot()
18.     {
19.         //calculate the shot
20.     }
21.  
22. }
23.  
24. public abstract class WeaponDecorator : Weapon
25. {
26.  
27.     protected Weapon _weapon;
28.  
29.     public WeaponDecorator(Weapon w)
30.     {
31.         _weapon = w;
32.     }
33.  
34.     public override void Shoot()
35.     {
36.         _weapon.Shoot();
37.     }
38.  
39. }
40.  
41. public class SilencerDecorator : WeaponDecorator
42. {
43.  
44.     public SilencerDecorator(Weapon w) : base(w)
45.     {
46.     }
47.  
48.     public override void Shoot()
49.     {
50.         _weapon.Range = 20.0f;
51.         base.Shoot();
52.     }
53.  
54. }
55.  

[edit]
Changed to work within the entity component design pattern used by MonoBehaviour

Code (csharp):

1.  
2. public abstract class Weapon : MonoBehaviour
3. {
4.  
5.     public virtual void Shoot()
6.     {
7.         //override
8.     }
9.  
10. }
11.  
12. public class Pistol : Weapon
13. {
14.  
15.     public float Range = 30;
16.  
17.     public override void Shoot()
18.     {
19.         //calculate the shot
20.     }
21.  
22. }
23.  
24. public abstract class WeaponDecorator : Weapon
25. {
26.  
27.     public Weapon DecoratedWeapon;
28.  
29.     public override void Shoot()
30.     {
31.         if(this.DecoratedWeapon == null) return;
32.         this.DecoratedWeapon.Shoot();
33.     }
34.  
35. }
36.  
37. public class SilencerDecorator : WeaponDecorator
38. {
39.  
40.     public override void Shoot()
41.     {
42.         this.DecoratedWeapon.Range = 20.0f;
43.         base.Shoot();
44.     }
45.  
46. }
47.  

Though if I'm going to be honest. This isn't the best mixture of the two, and I'd probably go a much different route. Just demonstrating how you should avoid the constructor.




As for your grip, it would wrap these.

The idea of your decorators is that they just wrap around your class you're decorating.

Code (csharp):

1.  
2. var weapon = new Grip(new Silencer(new Pistol)));
3.  

There you have a weapon that is a pistol decorated with a silencer and a grip. Your code just knows it's a weapon, in this case that weapon happens to be typed as a grip, but it doesn't care about that. It just cares that the method 'Shoot' exists, and the grip will apply it's decoration, then call shoot on silencer, which applies its decoration, and the finally calls shoot on pistol, which then actual calculates the shot.

 

Nope

 

I guess i understood

so if i want to add a Grip decorator what i have to use is something like this:

Code (CSharp):

1. public class GripDecorator : WeaponDecorator
2. {
3.     private WeaponComponent _wC;
4.    
5.     public GripDecorator(WeaponComponent wC)
6.     {
7.         _wC = wC;
8.         //Change Weapon attributes
9.     }
10.  
11.     public override void Shoot ()
12.     {
13.         base.Shoot ();
14.     }
15. }

But...Grip doesnt have to override Shoot isnt it? If not, When i do pistol = new GripDecorator() Shoot will not exist.

 

I must have edited my post after you read it, where I talked about the grip.

Sorry about that.

I'll quote it here:

Note how in my previous post I demonstrated that your decorator MUST call shoot on the weapon it is decorating. May that weapon it is decorating be a weapon as well.

Oh and I should also say, my decorator design is actually broken. Because the weapon you're decorating isn't necessarily typed correctly to have the 'Range' property on it.

Really decorators are for doing extra stuff on top of what the decorated class does. Not to necessarily modify that class. If it modifies it, there should be some interface through which to modify it in the abstract class that defines it.

 

I understand...But, in wich part do you reference teh public Weapon DecoratedWeapon; in the Decorator, in the ConcreteDecorator isnt it?

 

Grip Decorator must override the Shoot method too?

 

Well in the code I wrote, no, because the WeaponDecorator class takes care of calling the weapon. So you don't have to override it. But technically the Grip is calling Shoot... it's just taken care of in the super class.

 

but i have another Question.
I did all that and when i print i realize that Grip is modifing the Silencer weapon but no Pistol

So imagine that if i do.
Weapon pistol = new Pistol();
pistol = new Silencer();
pistol = new Grip(); //if i modify any params it will modify Silencer params but no pistol params

is that why you used a Weapon variable on the Decorator?