Using "onpreOpen"

bjb007 · Post by **bjb007** » Mon May 26, 2008 3:00 am

I have some code which sets up a lot
of info in arrays etc which I want to run
only once when the app. starts.

At the moment it's on the main card
so runs each time a button is clicked
and I can't find anywhere to put it so
that it only runs once.

Read about "onpreOpen" and "on preOpen card"
but confused about its use.

Any clarification appreciated.

Janschenkel · Post by **Janschenkel** » Mon May 26, 2008 5:42 am

The 'definitive' run-only-once message is 'startup'- but this will only get sent to your standalone application, never in the IDE.
So we had better find another message. I tend to put this initialization code into the 'preOpenStack' handler of the first card of my main stack, and I'll usually throw in a quick check to see if everything was initialized yet or not.

Code: Select all

on preOpenStack
  global gSettingsArray
  if the keys of gSettingsArray is empty then
    put the seconds into gSettingsArrayâ€™"startupTime"]
    ...
  end if
end preOpenStack

Hope this helped,

Jan Schenkel.

bjb007 · Post by **bjb007** » Mon May 26, 2008 6:00 am

Jan
What would I do without you?

I did think of using a variable to check if
the code had been run already.

I tried using the "preOpenStack" method but
found the disadvantage was that to debug
it the stack had to be closed then re-opened.

Rather annoying I found, so I think your suggested
method is better.

Janschenkel · Post by **Janschenkel** » Mon May 26, 2008 11:53 am

You can also trigger events yourself - in this case, you would go to the first card iof your main stack, and then open the Message Box, type in

Code: Select all

preOpenStack

and hit return.

If thye handler requires parameters, you can add them in the message box, just like you would call the handler from a piece of script.

Hope this helped,

Jan Schenkel.