Question About PreOpenStack

dunbarx at dunbarx at
Sun Sep 11 16:17:52 EDT 2011


Glad to see you have worked it out. It is a subtle danger, that other messages can insinuate themselves into what we try to contain in what we believe is a well defined situation. This is especially true with the very similar "open/preOpen" and "stack/card" messages.

Craig Newman

-----Original Message-----
From: Gregory Lypny <gregory.lypny at>
To: use-livecode <use-livecode at>
Sent: Sun, Sep 11, 2011 10:44 am
Subject: Re: Question About PreOpenStack

Hi Craig,

I had posted this right (see below) after you in message 21.  On reflection, the 
behaviour makes sense, and so does Mark’s suggestion that I move the main 
stack’s OpenStack handler to the card script.


> Hi Mark and Jacqueline,
> The substacks had PreOpenStack handlers that called a library stack and 
sometimes emptied out some fields, but what they did not have OpenStack 
handlers.  The absence of OpenStack handlers appears to have been the problem 
because, after the the sub-stack executes its own PreOpenStack, the main stack, 
for whatever reason, executes its OpenStack.  This, of course, can be disastrous 
if the main stack is intended to initialize an app or perhaps contains sensitive 
material that should not be revisited!  My fix is to include an OpenStack 
handler with nothing in it in every sub-stack in order to trap the message.
> on OpenStack
> ? Do nothing
> end OpenStack
> Gregory

On Sun, Sep 11, 2011, at 1:00 PM, use-livecode-request at wrote:

> Gregory, do you understand these nuances? Or is my original test, a simple 
mainStack/subStack file with a preOpenStack handler in each stack script, 
basically what you already have? Write back...
> Craig Newman

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