🪫 Generic PowerUps

PowerUps support generic type parameters. Using PowerUps as generic mixins can allow you to implement patterns that would otherwise be difficult, painful, or impossible to implement without expensive runtime reflection.

🔌 Creating a Generic PowerUp

Creating a generic PowerUp is the same as creating a generic class:

namespace GenericPowerUpExample;

using Godot;
using SuperNodes.Types;

[PowerUp]
public partial class MyPowerUp<T> : Node {
  public T Value { get; set; } = default!;

  public void OnMyPowerUp(int what) {
    if (what == NotificationReady) {
      if (Value is string) {
        GD.Print("You gave me a string!");
      }
      else if (Value is int) {
        GD.Print("You gave me an int!");
      }
      else {
        GD.Print("You gave me something else!");
      }
    }
  }
}

Any SuperNode that applies this PowerUp will gain a Value property of the type specified by T.

⚡️ Using a Generic PowerUp

To use a generic PowerUp, simply specify the type arguments when applying the PowerUp:

namespace GenericPowerUpExample;

using Godot;
using SuperNodes.Types;

[SuperNode(typeof(MyPowerUp<string>))]
public partial class MySuperNode : Node {
  public override partial void _Notification(int what);

  public void OnReady() => System.Diagnostics.Debug.Assert(Value is not null);
}

👯 Type Substitution

At compile time, the SuperNodes generator will substitute the type parameters on the PowerUp with the type arguments given to it from the [SuperNode] attribute.

Here's the generated code for the example above:

GenericPowerUpExample.MySuperNode_MyPowerUp.g.cs

#nullable enable
using Godot;
using SuperNodes.Types;

namespace GenericPowerUpExample {
  partial class MySuperNode
  {
    public string Value { get; set; } = default !; // <-- Type was changed!
    public void OnMyPowerUp(int what)
    {
      if (what == NotificationReady)
      {
        if (Value is string)
        {
          GD.Print("You gave me a string!");
        }
        else if (Value is int)
        {
          GD.Print("You gave me an int!");
        }
        else
        {
          GD.Print("You gave me something else!");
        }
      }
    }
  }
}
#nullable disable