The Finishing Touch

Everything seems fine? Don't forget that appearances can be deceptive! Click on the button Empty basket and try to select a product again. Nothing will happen! Of course it won't - because now you are trying to write into windows which no longer exist!

The solution? Check that the windows exist before modifying their content and create them if necessary with a simple call to ouvre_fenetres().

To include this check, just add the following lines in the switch structure of the function ajoute_objet.

  if ((caddie.closed) && (caisse.closed))
   ouvre_fenetres('white','white',200,300,200,300);


This instruction will call the method ouvre_fenêtres if the property .closed of the window objects caddie and caisse is true, i.e. if the windows are closed.


So now you think you've solved all your problems? Try to close one window only and select an item. Yet again, nothing happens. The previous conditional expression is only valid if both windows are closed. We must optimise this expression to take all possible scenarios into account:

if ((caddie.closed) || (caisse.closed))
{
if (!(caddie.closed))
  caddie.close();
if(!(caisse.closed))
  caisse.close();
ouvre_fenetres('white','white',200,300,200,300);
}

The first line checks to see if at least one of the windows is closed (both could be closed). If this is the case, we force the open one to close, and finally open them both again.

And if you'd like the items already ordered to reappear when the windows are closed then reopened, it can be done! Store the products in an array variable and add a change in the function ouvre_fenetres() so that it updates the child windows based on the array content. You could then make only one line appear per product type, updating the number of selected units. It's a good idea to experiment with what you have already learned.

You know how to make windows communicate, so now it's up to you to decide what they should say to one another.