Re: [Fxruby-users] Dialogues, and create.

[Lyle J. <jl...@cf...>]

Hugh Sasse Staff Elec Eng wrote:

>> Isn't the create() call propagated from parent to child?
> 
> Then why isn't it always?  I have found that I have to call create on
> the children before the parent, in the few cases I have done this so
> far.

Hugh,

Sorry for the delayed response. Joel was correct in his response that 
when you call create() on a parent window, it recursively calls create() 
on all of its child windows that exist at that time. Also, even though 
FXApp is not itself a "window", calling FXApp#create will call create() 
on all of the top-level windows (e.g. main windows and dialog boxes) 
that exist at the time create() is called.

So for the dialog.rb example program, the call to FXApp#create triggers 
calls to both DialogTester#create and FXTestDialog#create, since they 
are top-level windows and they have been instantiated before the call to 
FXApp#create. In turn those calls to DialogTester#create and 
FXTestDialog#create trigger recursive calls to create() for all of those 
windows' child windows.

> OK, but how do I use this?  I mean, I realise my heuristic was
> wrong, because the code works, but how do I revise it to fit with
> reality? :-)  Are there whole families of widgets and windows for
> which I can forget about the create() calls?  How do I look this
> information up?

I'm trying to think of any exceptions to the rule and I don't know that 
there are any. What may be tripping you up, and what frequently throws 
people, is that create() only realizes widgets that exist at the time 
that create() is called. In other words, say you construct a dialog box:

     dialog = FXTestDialog.new(...)

and then create it:

     dialog.create

Now if you were to add a new button to the dialog box immediately after 
you called FXDialogBox#create:

     button = FXButton.new(dialog, ...)

That button doesn't automatically get "created", because it didn't exist 
when you previously called create. You must go back and either call 
create() on the button itself:

     button.create

or, since calls to create() are recursive, you could call create() on 
the dialog again:

     dialog.create

Calling create() repeatedly on the same object is safe, at least for the 
built-in FOX classes. They will still recurse through the list of child 
windows, but only actually create the windows that haven't been realized 
yet.

Hope this helps,

Lyle