Handling "this" in helper objects

[maximinus]

I'm using Phaser 3 + ES6

I have a class defined in the normal way for a scene:

 

class TerminalScene extends Phaser.Scene {
    ...
};

Now I want to add a helper class of my own to manage some aspect. For instance, I have a class that handles some text displaying. But this class needs access to function this.add.text. For the moment I do this:

class SomeExample {
    constructor(func_add_text) {
        this.add_text = func_add_text;
    }

    add(string) {
        func_add_text(......);
    }
};


// to call the add function in SomeExample:

var my_class_instance = new SomeExample(this.add.text.bind(this.add));
my_class_instance.add('Hello, World');

There must be a better way of doing this. In other libraries, I would have access to the function by importing. What am I missing?

[necKros]

Scene.add is already a helper plugin that adds common GameObjects to the scene it pertains to.

Given the heavy focus Phaser 3 has on scenes, almost all your classes will need the scene as a parameter for the constructor. That way you can add objects with the add function:

class MyObject {
	constructor(scene) {
		scene.add.image(0,0,'foo')
	}
}

Or add them with add.existing, which you will need if you are creating classes that extend any GameObject:

class MyObject {
	constructor(scene) {
		let image = new Phaser.GameObjects.Image(scene, 0, 0, 'foo')
		scene.add.existing(image)
	}
}

class MyObject extends Phaser.GameObjects.Image {
	constructor(scene, x, y, key, frame) {
		super(scene, x, y, key, frame)
		scene.add.existing(this)
	}
}

[iKest]

class SomeExample {
    constructor(func_add_text) {
        this.add_text = func_add_text;
    }

    add(string) {
        return this.add_text(......);
    }
};


// to call the add function in SomeExample:

var my_class_instance = new SomeExample(this.add.text);
my_class_instance.add('Hello, World');

or

class SomeExample {
    constructor(func_add_text, scope) {
        this.add_text = func_add_text;
this.scope = scope
    }

    add(string) {
        this.add_text.call(this.scope, string)
    }
};


// to call the add function in SomeExample:

var my_class_instance = new SomeExample(add.text, this);
my_class_instance.add('Hello, World');

 

[maximinus]

Thanks all. Passing over the scene (i.e, "this" from the scene object) seems the best way, although I was trying to avoid having a reference to all of it. At least it's consistent and avoids all those .bind() calls.