ReplaceGlobalReferenceWithGetter1.ts

class RegisterSale {
    // more code...

    public addItem(code: Barcode): void {
        //!! After Extract Method
        const newItem = this.getInventory().getItemForBarCode(code);
        this.items.push(newItem);
    }

    //!! Extracted method. Now we can apply Subclass & Override Method here!!
    private getInventory(): Inventory {
        // still using the Singleton!!
        return Inventory.getInstance();
    }

    // more code...
}