Re: catch-cancel

[alice@digitool.com (Alice Hartley)]

At 4:55 PM 5/31/95, Michael Korcuska wrote:
>In article <gclements-3105951036250001@mac21_58.keps.com>,
>gclements@keps.com (Geoffrey Clements) wrote:
>
>>
>> I belive the problem is that the scope that (throw *tag* "Cancelled") is
>> different from the scope that (catch *tag ...) is set up in. The throw is
>> called from low level event handling code which is different from where
>> the loop is running. I also think that the throw-cancel/catch-cancel
>> mechanism is reserved for modal-dialogs. (i'm relatively new to MCL so I
>> could be wrong about this.)
>
>(my email reply to you previously was incorrect, Geoff.  sorry about that)
>
>I originally suspected this too.  But if this were the case then (throw
>:foo) would cause an error.  My best guess (from Chris Wisdo actually) is
>that the event processing code is setting up a (catch :cancel) inside the
>dynamic scope of my catch.  Anybody at Apple/Digitool care to comment on
>this?
>

Yes its true that there is a (catch :cancel ...) withing the event processing
code. It should probably be mentioned somewhere in the documentation
that MCL uses the catch tag :cancel for some internal purposes.


Alice@digitool.com