Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!ucsd!ucbvax!bloom-beacon!rsfinn
From: rsfinn@athena.mit.edu (Russell S. Finn)
Newsgroups: comp.sys.mac.programmer
Subject: Re: @ Operator & Keydown events in Think Pascal?
Message-ID: <1990Nov2.235814.25686@athena.mit.edu>
Date: 2 Nov 90 23:58:14 GMT
References: <3234.27315d8c@cc.nu.oz.au>
Sender: daemon@athena.mit.edu (Mr Background)
Organization: Massachusetts Institute of Technology
Lines: 40

In article <3234.27315d8c@cc.nu.oz.au> mebhl@cc.nu.oz.au writes:
>The crucial function has the form:
>
>   function TestKey (i: longint): boolean;
>      var
>         myKeys: keyMap;
>   begin
>      GetKeys(myKeys);
>      TestKey := BitTst(@myKeys[1], i)
>   end;
>
>When this is run, THINK Pascal tells me that:
>
>   @ can't be applied to a component of a packed type.

Right, because KeyMap is defined as PACKED ARRAY[0..127] OF BOOLEAN.

>But the code obviously used to work. What's changed, and what can I change
>get it to work again? 

In versions of THINK Pascal earlier than 3.0, PACKED ARRAY OF BOOLEAN
was not implemented, and so KeyMap had to be defined as PACKED
ARRAY[0..3] OF LONGINT instead.  This required the circumlocution
described above.  

Since version 3.01, PACKED ARRAY OF BOOLEAN is supported correctly,
and you can now just say

	TestKey := myKeys[keyCode]

where keyCode is the code of the desired key (see the Event Manager
chapter of Inside Macintosh).

Note that if you're just interested in modifier keys, you can simply
call GetNextEvent and examine the modifier field of the EventRecord,
even if GetNextEvent returned FALSE (as someone has previously pointed
out).  Of course, this works for WaitNextEvent also.

-- Russ
rsfinn@{athena,lcs}.mit.edu