Path: utzoo!attcan!uunet!ncrlnk!ncr-sd!hp-sdd!hplabs!well!jdevoto
From: jdevoto@well.UUCP (Jeanne DeVoto)
Newsgroups: comp.sys.mac.hypercard
Subject: Re: Is it possible to test for the existance of an object?
Message-ID: <10093@well.UUCP>
Date: 23 Dec 88 04:22:37 GMT
References: <82129@sun.uucp> <258@gloom.UUCP>
Reply-To: jdevoto@well.UUCP (Jeanne DeVoto)
Organization: Whole Earth 'Lectronic Link, Sausalito, CA
Lines: 22


You can check for the existence of a card by noting that a failed "go"
command sets the value of the result function. A script would look like
this:
    on mouseDown
      lock screen  -- hide following shenanigans from users
      go to card "Am I Here?"
      if the result is not empty then
        -- card doesn't exist
      else
        -- it does exist
        go recent card -- get back where you came from
      end if
      unlock screen
    end mouseDown

The only way I know of to test for the existence of a field or button
is to use a repeat loop to step through each field (or button) on the 
current card and check whether that one is the one you want.

jeanne a. e. devoto
jdevoto@well.UUCP