Not sure how to make use of interface implements with array

1

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i don’t know what to do on this

2

as a code block (with the flixel stuff removed as that’s not actually significant to this problem)

class Test {
	var thingArrayVar:Array<IThing>;

	public function doStuff() {
		thingArray(new Array<ThingWithInterface>());
	}

	public function thingArray<T:IThing>(arr:Array<IThing>):Bool {
		thingArrayVar = arr;
		return arr[0].foo;
	}
}

interface IThing {
	public var foo:Bool;
}

class ThingWithInterfaceimplements implements IThing {
	public var foo:Bool = true;

	public function new() {}
}
3

Try this

class Test {
    var thingArrayVar:Array<IThing>;
  
    public function new() {}

	public function doStuff() {
		thingArray(new Array());
	}

	public function thingArray(arr:Array<IThing>):Bool {
		thingArrayVar = arr;
		return arr[0].foo;
	}
}

function main() {
  var test = new Test();
  test.thingArray([new ThingWithInterfaceimplements()]);
  test.doStuff();
}
4

The problem is with variance.

Here’s an example of why that won’t work:

class Test {
    
    static function thingArray(arr:Array<IThing>) {
      arr.push(new Thang());
      return arr;
    }
  
  	static function main() {
      	var arr = new Array<Thing>();
        thingArray(cast arr);// let's make the compiler accept it
      	arr.pop().bar();// kabooom!
  	}
}

interface IThing {}

class Thing implements IThing {
 
  	public function bar() {}
    public function new() {}
}

class Thang implements IThing {
     public function new() {}
}

In your code, you could make it function thingArray<T:IThing>(arr:Array<T>) for example. Then it would work with an array of any type that is an IThing.