koobas.hobune.stream
Polymorphism on member attribute
This issue has been difficult for me to search, largely because the keywords bring up similar, but not exactly the same scenarios.
.
Basically what I'm trying to do is have a single GameManager class with a list of Player objects, but each class that inherits from GameManager will have some child of Player as well. How can I construct an array in GameManager to reduce or eliminate the amount of casting necessary on the list in a GameManager child.
.
Here's an example. The scene containing GameManagerChild is guaranteed to only contain PlayerChild objects.
.
public class GameManager : MonoBehavior
{
protected Player[] _players;
protected void Start()
{
InitializePlayers();
}
protected void InitializePlayers()
{
_players = FindObjectsOfType(typeof(Player)) as Player[];
}
}
public class GameManagerChild : GameManager
{
void Update()
{
DoSomethingWithPlayers();
}
void DoSomethingWithPlayers()
{
foreach (PlayerChild player in _players)
{
player.SomeMethodSpecificToPlayerChild();
}
}
}
.
One solution could be to make InitializePlayers abstract and each child of GameManager would need to populate the list with appropriate children of Player, but this would still require casting each time we want to act on an item in _player from a GameManager child.
.
Any better design suggestions?
I don't quite understand the usage of your classes here. Isn't a Game$$anonymous$$anager meant to be a singleton? Why do you derive other classes from this class?
@Bunny83, the game is actually a series of $$anonymous$$igames, so each game will have entirely different mechanics, but contain similar actions at their core. e.g. each game has a set of players, a win condition, the ability to exit to the game selection screen, etc
The only singleton currently is a GameControls$$anonymous$$anager singleton which keep controls for each player universal between the scenes.
I'm not sure what's the point of all this. Maybe you should choose a better / more descriptive name of your class. Does your class really "mangage the game"? If not you should use a different name.
However from your description you may want to do something like this:
public class GameManager<TItemType> : MonoBehavior where TItemType : Player
{
protected TItemType[] _players;
protected void Start()
{
InitializePlayers();
}
protected void InitializePlayers()
{
_players = FindObjectsOfType<TItemType>();
}
}
public class GameManagerChild : GameManager<PlayerChild>
{
void Update()
{
DoSomethingWithPlayers();
}
void DoSomethingWithPlayers()
{
foreach (PlayerChild player in _players)
{
player.SomeMethodSpecificToPlayerChild();
}
}
}
Note that you can't attach a "GameManager" to a gameobject as generic classes are not supported. However derived concrete classes do work just fine. So "GameManagerChild" can be attached to a gameobject.
I believe the Game$$anonymous$$anager is appropriately named. The classes I included in the example are stripped-down versions to focus entirely on the question, so its understandable that the intention isn't clear.
The Game$$anonymous$$anagers be made to manage the scene, players, and win conditions of each $$anonymous$$igame. Basically the whole flow of the game and high-level interactions between the objects.
I think the construction above would work. I'm still picking up C#, so I'll need to read up on Generic vs. Derived Concrete Classes, since at first glance this just looks like a Generic class to me, but I think I see the distinction.
I guess TItemType is just a common na$$anonymous$$g convention for these constructs? Still trying to find a clear answer through google.
This worked for what we needed. Appreciate the comments on the design. I'll keep thinking this over.
