mckernon wrote:
>  I can't for the life of
> me figure out where the replacement for PG's filters belongs in the
> structure of an Appearance Project.
< snip >
> *How can IF 0 THEN RETURN ever execute, since 0 would always be false?
> *Where would the filter code RETURN to, without it getting called from
> anywhere?

IF 0 THEN RETURN is merely a trick to force the compiler to insert a 
MacsBug label. The return is indeed never executed. The real RETURN is 
in your xxxx.MAIN file (see below).

> *Where in this event loop do I stash code for filters?

Here are some notes I made on 'How the PG runtime works'. They don't 
exactly answer your question, but...


A core of a PG program resides in Runtime.INCL. It consists in setting 
up handlers, with the GOSUB format (obsolete in a non-PG program), and 
then entering an infinite loop:

// in Runtime.INCL
ON BREAK      GOSUB "PG:Chk Break"
...
ON EVENT      GOSUB "PG:Event"
...
DO
  HANDLEEVENTS
UNTIL 0

The all-important handler PG:Event in simplified form just calls 
PG:Main Program, again by GOSUB.

// in Runtime.INCL
"PG:Event"
gAction  = _otherAction
GOSUB "PG:Main Program"
RETURN

"PG:Main Program"
// end of Runtime.INCL


The subroutine named PG:Main Program is a multi-file monster that 
contains all the filters, and ends with a RETURN in your xxxx.MAIN file

// Filters go here. They work by inspecting
// gAction and other PG global variables
// and then calling local FNs as required.

// in xxxx.MAIN
SELECT gAction
CASE _mainAction   :GOSUB "Action:Main"
CASE _menuAction   :GOSUB "Action:Menu"
CASE _buttonAction :GOSUB "Action:Button"
CASE _mouseAction  :GOSUB "Action:Mouse"
CASE _windowAction :GOSUB "Action:Window"
CASE _fieldAction  :GOSUB "Action:Field"
CASE _otherAction  :GOSUB "Action:Other"
END SELECT:RETURN    //  <-- return to PG:Event


Robert P.