Path: utzoo!utgpu!jarvis.csri.toronto.edu!torsqnt!tmsoft!masnet!canremote!beard@ux1.lbl.gov
From: beard@ux1.lbl.gov@canremote.uucp (beard@ux1.lbl.gov)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Think C 32K global data l
Message-ID: <89122504043334@masnet.uucp>
Date: 21 Dec 89 05:04:00 GMT
Organization: Canada Remote Systems Limited, Mississauga, ON, Canada
Lines: 62

From: beard@ux1.lbl.gov (Patrick C Beard)
Subj: Think C 32K global data limit: workaround?
Orga: Lawrence Berkeley Laboratory, Berkeley

In article <37420@apple.Apple.COM> keith@Apple.COM (Keith Rollin)
writes: >Ned,
>
>One of us - either you or me - doesn't know what you're talking
about. When you >say that it doesn't address the issue of initialized
data, what do you mean?  >After all, MakeA5World is supposed to do
this for you. By "this", I mean that  >it creates space for your
data, and initializes it all to zero, or with  >predefined values if
you are using C or Assembly.

This is true.  I've taken the tech note to task by creating
independent code resources written in C++ that have global variables
with initialized data. The ability to stuff objects in a code
resource is really handy, I've written simple interfaces (objects)
for encapsulating the nastiness that goes along with this MakeA5World
stuff and hides it from me.

>If you have other issues with the technote (like, for example, I
forgot to  >suggest that one call InitGraf when setting up his/her A5
world), then please >let me know.

I've tried calling InitGraf to initialize my code resource's A5
world.  It may have been that something else was making it crash, but
is this a valid thing to do so that the A5 world will have properly
initialized quickdraw variables?  I've been stuffing values into the
qd globals and it works.

>Finally, I'd like to hear where you read "and I'll tell you how to
live >without it." I tried to be accomodating. In cases where I said
you couldn't do >something, I also tried to explain why. If I failed
in some places please let >me know.

What I want to know is when you will tell us how to create jump
tables for our multi-segmented code resources.  THINK C lets us do
that.  Take us one step closer to the capabilities they provide and
the MPW languages will become a viable development environment for
non-application code.

Why?  I want virtual functions in my code resources!  Why must they be
implemented (for C++ or Object Pascal) as jump table entries?  I
don't see why the method tables can't be resolved at data
initialization time.  It's easy to write code that computes the
absolute addresses of methods and stuffs it into a table of function
pointers.

Thanks for global data, now give me jump tables!  Then, rewrite MacApp
in C++, then..., well I can dream.


---------------------------------------------------------------------
---------- -  Patrick Beard, Macintosh Programmer                    
   (beard@lbl.gov) - -  Berkeley Systems, Inc.  ".......<dead
air>.......Good day!" - Paul Harvey  -
---------------------------------------------------------------------
----------
---
 * Via MaSNet/HST96/HST144/V32 - UN Mac Programmer
 * Via Usenet Newsgroup comp.sys.mac.programmer