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From: ech@cbnewsk.att.com (ned.horvath)
Newsgroups: comp.sys.mac.hypercard
Subject: Re: Question about protocol for trapping menu items.
Message-ID: <1991Jan24.162145.16211@cbnewsk.att.com>
Date: 24 Jan 91 16:21:45 GMT
References: <48422@apple.Apple.COM>
Organization: AT&T Bell Laboratories
Lines: 37

In article <1991Jan23.234729.7744@world.std.com> ralph@world.std.com
(Ralph Lombreglia) writes:
>Why does the following *not* work?

>on doMenu what
>  if what is "Compact Stack" then
>    close window "MyPalette"
>    pass doMenu
>    palette "MyPalette", "345,80"
>  else pass doMenu
>end doMenu

From article <48422@apple.Apple.COM>, by jdevoto@Apple.COM (Jeanne A. E. DeVoto):
> The reason this doesn't work is that the "pass" keyword halts the current
> handler. "Pass" means "forget this handler and just pass the message on
> to the next level of the message hierarchy."
> 
> This should work:
> 
>   on doMenu theItem
>     if theItem is "Compact Stack" then
>       close window "MyPalette"
>       send "doMenu Compact Stack" to HyperCard -- avoids recursion
>       palette "MyPalette", "345,80"
>     else pass doMenu
>   end doMenu

This isn't quite satisfactory: in general, you want to give all the rest
of the doMenu handlers in the handler chain a shot at the Compact Stack
message.  But as far as I know, the only way to refer to "the next handler
in the chain" is to pass to it.

Why is this reminiscent of "don't tail patch"?

=Ned Horvath=
ehorvath@attmail.com
has to know