Game Craft Conference 2017 Анатолій Ландишев - “Незв’язний код у Unity” Сайт: http://gamecraftconf.com FB page: http://fb.com/GameCraftConference

1. DECOUPLED CODE
IN
Speaker: Anatolii Landyshev

2. • Founder, CTO of Patriotic Games
• 7 years of experience in
• Unity Certified Developer
http://patriotic.games
Anatolii Landyshev

3. Why ?

4. • Max number of supported platforms
Why ?

5. • Best VR & AR support
Why ?

6. • 3rd party services support Unity
Why ?

7. • Editor
Why ?

8. Component Architecture

9. Components instead of Inheritance

11. MonoBehaviour
Player Spaceship
AIPlayer
HumanPlayer
Scout
Defender
Cruiser

12. MonoBehaviour
Player Spaceship
AIPlayer
HumanPlayer
Scout
Defender
Cruiser

13. MonoBehaviour
Player Spaceship
AIPlayer
HumanPlayer
Scout
Defender
Cruiser

14. AIPlayer
Defender
Gun
Composition over inheritance

15. AIPlayer
Defender
Gun
Composition over inheritance

16. AIPlayer
Player
AI
Render
Health
Team
Defender
Move
Render
Health
Team
Gun
Components instead of inheritance

17. AIPlayer
Player
AI
Render
Health
Team
Defender
Move
Render
Health
Team
Gun
Components instead of inheritance

18. AIPlayer
Player
AI
Render
Health
Team
Gun
Defender
Move
Render
Health
Team
Gun
Components instead of inheritance

19. AAA games with Unity-like architecture

20. • No constructor in components
Unity architecture drawbacks
public class X : MonoBehaviour {}
…
var x = new GameObject().AddComponent<X>();

21. • No single entry point
Unity architecture drawbacks
void main() {}

22. How to design code in Unity?

23. The common architecture in Unity

24. Most Unity tutorials use Singletons

25. Most Unity tutorials use Singletons

26. Singleton
• Represents GLOBAL STATE in your code
• Programs using global state are VERY
difficult to test and debug
• Programs relying on global state HIDE their
dependencies

27. class X {
…
public X() { … }
public int DoSomething() { … }
}
int a = new X().DoSomething();
int b = new X().DoSomething();
Global State

28. class X {
…
public X() { … }
public int DoSomething() { … }
}
int a = new X().DoSomething();
int b = new X().DoSomething();
Global State
Does a == b or a != b?

29. Global State
int a = new X()  X
Y
Q
Z

30. Global State
int a = new X()  X
Y
Q
Z
int b = new X()  X
Y
Q
Z

31. Global State
int a = new X() 
.DoSomething()
X
Y
Q
Z
int b = new X() 
.DoSomething()
X
Y
Q
Z
a == b

32. Global State
int a = new X() 
.DoSomething()
X
Y
Q
Z
int b = new X() 
.DoSomething()
X
Y
Q
Z
a != b
GS

33. Same in Unity
class X : MonoBehaviour {
public int DoSomething() { … }
}
X x1 = new GameObject().AddComponent<X>();
int a = x1.DoSomething();
X x2 = new GameObject().AddComponent<X>();
int b = x2.DoSomething();
Does a == b or a != b?

34. Deceptive API

36. Deceptive API
[SerializeField] GameObject _enemyPrefab;
void SpawnEnemy() {
var enemy = Instantiate(_enemyPrefab);
}

38. Deceptive API
[SerializeField] GameObject _enemyPrefab;
void Awake() {
var enemy = Instantiate(_enemyPrefab);
}

39. Deceptive API
[SerializeField] GameObject _enemyPrefab;
void Awake() {
var enemy = Instantiate(_enemyPrefab);
}

40. Deceptive API
[SerializeField] GameObject _enemyPrefab;
[SerializeField] PlayerHealth _player;
void Awake() {
GameManager.Instance.Player = _player;
var enemy = Instantiate(_enemyPrefab);
}

41. Deceptive API
[SerializeField] GameObject _enemyPrefab;
[SerializeField] PlayerHealth _player;
void Awake() {
GameManager.Instance.Player = _player;
var enemy = Instantiate(_enemyPrefab);
}

42. Deceptive API
[SerializeField] GameObject _enemyPrefab;
[SerializeField] PlayerHealth _player;
void Start() {
GameManager.Instance.Player = _player;
var enemy = Instantiate(_enemyPrefab);
}

43. Deceptive API
A a = new A();
B b = new B();
a.x();
b.z();
a.y(b);
B b = new B();
b.z();
A a = new A();
a.x();
a.y(b);
• Code should be commutative (a*b = b*a)
• The above code will fail if there’s Global State

44. Singleton
public class GameSettings : MonoBehaviour {
public static GameSettings Instance;
private GameObject _state1;
private GameObject _state2;
private GameObject _state3;
void Awake() {
if (Instance == null)
Instance = this;
else if (Instance != this)
Destroy(this);
}

45. Singleton
public class GameSettings : MonoBehaviour {
private GameObject _state1;
private GameObject _state2;
private GameObject _state3;
void Awake() {}
• Class no longer enforces its “singletoness”
• Application code creates only one instance

46. Better API – Method Injection
[SerializeField] GameObject _enemyPrefab;
[SerializeField] PlayerHealth _player;
void Start() {
var enemy = Instantiate(_enemyPrefab);
var enemyMovement =
enemy.GetComponent<EnemyMovement>();
enemyMovement.Init(_player, …);
}

47. Better API – Property Injection
[SerializeField] GameObject _enemyPrefab;
[SerializeField] PlayerHealth _player;
void Start() {
var enemy = Instantiate(_enemyPrefab);
var enemyMovement =
enemy.GetComponent<EnemyMovement>();
enemyMovement.Player = _player;
}

48. Dependency Injection

49. Dependency Injection
- better than Singleton

50. • Constructor injection
Types of Injection
class X {
private Y _y;
public X(Y y) { _y = y; }
…
}
var x = new X(y);

51. • Constructor injection
Types of Injection
class X {
private Y _y;
public X(Y y) { _y = y; }
…
}
var x = new X(y);
var z = new Z(x);

52. • Method Injection
Types of Injection
class X {
private Y _y;
public void SetY(Y y) { _y = y; }
…
}
var x = new X();
x.SetY(y);

53. • Method Injection
Types of Injection
class X {
public void Init(Y y, Z z) {…}
…
}
var x = new X();
x.Init(y, z);

54. • Property Injection
Types of Injection
class X {
public Z Z {get; set;}
…
}
var x = new X();
x.Z = z;

55. • Constructor injection
• Method injection
• Property injection
Types of Injection

56. • Constructor injection
• Method injection
• Property injection
Types of Injection in Unity

57. X x = new GameObject().AddComponent<X>();
x.Init(a, b, c);
Y y = new GameObject().AddComponent<Y>();
y.x = x;
Z z = Instantiate(_zPrefab);
z.Init(x, y);
Dependency Injection in Unity

58. Composition Root

59. House Door Door Nap
Composition Root Example

60. Dependency Injection done wrong
public class DoorNap {
public DoorNap(Color color) {…}
}
public class Door {
public Door(Color color, Color doorNapColor) {
…
_doorNap = new DoorNap(doorNapColor);
}
}

61. Dependency Injection done wrong
public class House {
public House(Color wallsColor,
Color doorColor, Color doorNapColor) {
…
_door = new Door(doorColor, doorNapColor);
}
}

62. Dependency Injection done right
public class DoorNap {
public DoorNap(Color color) {…}
}
public class Door {
public Door(Color color, DoorNap doorNap) {
…
_doorNap = doorNap;
}
}

63. Dependency Injection done right
public class House {
public House(Color wallsColor, Door door) {
…
_door = door;
}
}

64. Dependency Injection done right
public class HouseFactory {
public House CreateHouse() {
var doorNap = new DoorNap(Color.yellow);
var door = new Door(Color.brown, doorNap);
var house = new House(Color.white, door);
return house;
}
}

65. Composition Root
public class HouseFactory {
public House CreateHouse() {
var doorNap = new DoorNap(Color.yellow);
var door = new Door(Color.brown, doorNap);
var house = new House(Color.white, door);
return house;
}
}

66. Composition Root
in Unity - Script

67. Composition Root
in Unity - Script
var frisbeeThrower
= new GameObject("FrisbeeThrower")
.AddComponent<FrisbeeThrower>()
.Init(_frisbeePrefab, _hand, _placeForFrisbee,
_throwHandAnimator, _head);

68. Composition
Root in Unity
- Scene

69. Composition
Root in Unity
- Scene
No support for
C# Interfaces

70. Initialization order matters!

71. Desired Architecture

72. Desired Architecture

73. Reusability via Decoupling

74. Reusability via Decoupling

75. Reusability via Decoupling

76. • Rely on interface, not implementation
How to decouple code?
public interface IXHandler {
void DoSomething();
}
class X {
public X(IXHandler handler) {…}
}

77. • Rely on interface, not implementation
How to decouple code?
class Y : IXHandler {
public void DoSomething() {…}
}
class Z : IXHandler {
public void DoSomething() {…}
}

78. • Use delegates
How to decouple code?
class X {
public X(Action doSomething) {…}
…
}
void DoSomething() {…}
var x = new X(DoSomething);

79. • Use events
How to decouple code?
class X {
public event Action OnX;
}
void DoSomething() {…}
var x = new X();
x.OnX += DoSomething;

80. • Use UnityEvent
How to decouple code?
class X {
public UnityEvent OnX;
}
void DoSomething() {…}
var x = new X();
x.OnX.AddListener(DoSomething);

81. • Use UnityEvent
How to decouple code?

82. • Supports methods, properties, events
• Best performance
• Supported by DI Containers
• Supported by Moq frameworks
• Unsupported in Unity Inspector
Using C# interfaces is preferred

83. IOC in

84. Components instead of Inheritance

85. How about Components
instead of Interfaces?

86. Component + UnityEvent
instead of Interface
public class XHandler : MonoBehaviour {
public UnityEvent OnDoSomething;
public void DoSomething() {
OnDoSomething.Invoke();
};
}
public XHandler Handler;
Handler.DoSomething();

87. Component + UnityEvent
instead of Interface
public class XHandler : MonoBehaviour {
public UnityEvent OnDoSomething;
public void DoSomething() {
OnDoSomething.Invoke();
};
}
[SerializeField] XHandler _handler;
_handler.DoSomething();

88. Component + UnityEvent
instead of Interface

89. Component + UnityEvent
instead of Interface

90. Component + UnityEvent
instead of Interface
• Supports methods, properties, events
• Supported by some DI Containers
• Supported by Moq frameworks
• Supported in Unity Inspector
• Lower performance due to UnityEvent

91. Conclusion
• Singletons and Global State cause problems
• Dependency Injection is better
• Interfaces, Delegates, Events,
Component + UnityEvent are the ways to
decouple your module from rest of code

92. Questions?