Re: unwind-protect&choose-file-dia

[straz (Steve Strassmann)]

At  4:57 AM 8/23/94 +0000, KHOSLA@AppleLink.Apple.COM (Khosla Consulting, Ashok Khosla,PAS wrote:
 >I'm having trouble getting the choose-file-dialog to work correctly when
 >cancelled - Here is a sample:
 > 
 >(progn (setf aFileName "Unnamed")
 >           (setf aFileName (unwind-protect
 >                             (choose-file-dialog :mac-file-type :|TEXT|)
 >                             "cancelled"))
 >           aFileName)
 > 
 >When the SFGetFile appears, if I hit escape or cancel, the dialog unwinds past
 >my unwind protect, and I never get aFileName set to "cancelled".
 > 
 > 
 >Any ideas?
 > 

The Cancel button throws a :cancel tag, which isn't caught by anything
in your code, so it throws all the way to the top level listener.
The second setf never gets a chance to execute, since the "setf" itself
is not in the cleanup clause of your unwind-protect.

How about something like this instead?

(let ((name (catch :cancel 
                (choose-file-dialog :mac-file-type :|TEXT|))))
    (setf aFileName (if (eq name :cancel) 
                      "cancelled"
                      name)))