Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!apple!jkc
From: jkc@Apple.COM (John Kevin Calhoun)
Newsgroups: comp.sys.mac.hypercard
Subject: Re: AppleEvent limitation in HC 2.1?
Message-ID: <53931@apple.Apple.COM>
Date: 13 Jun 91 01:55:18 GMT
References: <1991Jun12.154845.1@f.adelaide.edu.au> <53912@apple.Apple.COM>
Organization: Apple Computer Inc., Cupertino, CA
Lines: 42


Dr. Pradhan and I exchanged a couple of e-mail messages, and we
finally figured out what the problem was.  He was sending HyperCard
a line of HyperTalk like the following:

     put "<string over 250 characters long>" into field x

I don't know why I didn't remember this before -- HyperTalk can't
handle single lines longer than 255 characters!  Therefore the
line above won't work, whether you try to execute it locally or
send it to HyperCard in a "do script" event.

Because of this limitation, neither the "do script" event nor the
"evaluate expression" event is a good way to send large chunks of
data to HyperCard.  I suggested that he define an Apple event for
setting the contents of a field, class "WILD" and id "SFLD", like so:

  on appleEvent class,id,sender
    if class & id is "WILDSFLD" then  -- class = "WILD", id = "SFLD"
      request appleEvent data  -- direct parameter contains field number
      put it into fieldNum
      request appleEvent data of type 'STUF'  -- contains text for field
      put it into theStuff
      if there is a field fieldNum
      then put theStuff into field fieldNum
      else reply error "No such field"
    else pass appleEvent
  end appleEvent

You can make this event a great deal fancier -- specifying whether the
field is a card or background field, specifying it by name, number, or
id, specifying even the card and stack to which it belongs.            

In the future, when HyperCard supports the Apple event object model
and the core suite of Apple events, you would probably use the standard
"set data" event instead of a made-up one like "SFLD".  But in the
meantime, you're free to define and use Apple events for your own
purposes and to tell HyperCard how to handle them by writing appleEvent
handlers.

Kevin Calhoun
jkc@apple.com