Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!rutgers!apple!keith
From: keith@Apple.COM (Keith Rollin)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Think C 32K global data limit: workaround?
Message-ID: <37420@apple.Apple.COM>
Date: 20 Dec 89 03:26:23 GMT
References: <5837@internal.Apple.COM> <1672@cbnewsk.ATT.COM>
Organization: Apple Computer Inc, Cupertino, CA
Lines: 55

In article <1672@cbnewsk.ATT.COM> ech@cbnewsk.ATT.COM (ned.horvath) writes:
>In article <1664@cbnewsk.ATT.COM> I wrote:
>> So far, the MPW linker won't give non-apps globals, hence no method 
>> dispatch tables.
>
>From article <5837@internal.Apple.COM>, by lsr@Apple.COM (Larry Rosenstein):
>> See Tech Note #256.  
>
>I've seen it.  It's an excellent example of "tell me what you need, I'll
>tell you how to live without it."  The suggestion is incomplete -- e.g.
>initialized data is not addressed -- and requires the connivance of the
>underlying application.  I don't have that connivance with, say, DAs.
>Or other drivers.  Or FKEYs. Or any other code resource intended to exist
>independently of a PARTICULAR application.  Or even with HyperCard -- the
>example in the technote requires careful attention in the Hypercard script
>to making sure the XCMD-with-persistent-data is properly set up and torn
>down -- an error in that script hoses memory at random, a very user-
>unfriendly XCMD to put in the hands of "the rest of us."

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.

As for DA's, you don't have to rely on any host application. You can just
stick your A5 reference into dCtlStorgage. Same with other drivers. As for
FKEYs, you can use a hack that I used originally, which was to link in a
little assembly PROC that I jammed my A5 reference into.

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. In particular, I'd like to hear your suggestions on getting rid
of the global data without getting some sort of close message. And remember,
you don't HAVE to use persistant global data. Nothing in the rules about that.
I just mentioned it and showed how to do it in the (inevitable) case that
someone asked.

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.

All of this applies to EVERY TECHNOTE, and to EVERY READER of this network: if
you have issues with out Technotes...then let us know! Don't go flaming on
the nets. We're here. We listen. These technotes are for you, and we want them
to be useful...

-- 
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Keith Rollin  ---  Apple Computer, Inc.  ---  Developer Technical Support
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"Argue for your Apple, and sure enough, it's yours" - Keith Rollin, Contusions