[REBOL] Re: [view] Problems with /new and not /new
From: nitsch-lists:netcologne at: 14-Aug-2004 23:54
A few words about view/ view/new and event-loop:
On Samstag, 14. August 2004 01:05, Izkata wrote:
> Using view/new works just fine.. The script continues as it should..
>
> But for some reason, even if I hadn't used view/new in the script yet,
> using only view layout [blah blah] causes the script to continue on and not
> halt.
> It usually happens when I click a button in a layout that calls a function
> that
> opens another. (Did that make sense?)
Makes sense :)
Thats because 'view checks if any windows are open. It is not meant to block,
but somebody has to start the event-loop. And there is no way to check if
events are running already. So by convention, if there are open windows,
there is a running event-loop too.
Another difference between view and view/new: view closes the current window.
view/new adds another one.
In combination you can make kind of "browser" where you do go to other scripts
when the user presses a button:
as convention each script makes a layout and ends with
view my-layout
now the first script runs. it sees there is no open window, so starts the
event-loop (blocks).
now the user presses button, we do second script.
This script does its view, and now a window is open:
1) view closes the old window. Thats good. otherwise we would have lots of
death, uninteresting windows some clicks later.
2) it sees a window is open, so there should be a event-loop. So it does not
start a new one (means does no 'wait, 'do-events or such).
3) does not block. so the script returns. 'view was the last command, so that
makes no difference.
So rebol does some returns, to the button-press, then to the first event-loop.
There are no more information about doing the new script on the return-stack.
So you can do an unlimited amount of scripts.
You can also do the same script alot of times. button-press -> change data,
save data, do script again. No stack-flooding. Kind of tail-recursion.
Or you can use that like a browser: a script is a "page", has some content and
some links (buttons with "do other page"). The other page has some links too.
All pages have a "do %main-menu.r". And you have a flexible application where
you quickly can add funtions.
Only problem are the jumping windows, but for a prototype ok.
>
> -Izzy boy ^.^ (Thanx for any help if you understood my request)
-Volker
