Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!mit-eddie!uw-beaver!cornell!rochester!pt.cs.cmu.edu!cadre!pitt!unix.cis.pittsburgh.edu!adams3
From: adams3@unix.cis.pittsburgh.edu (Larry Adams)
Newsgroups: comp.sys.mac.programmer
Subject: Alert problems
Message-ID: <18282@unix.cis.pittsburgh.edu>
Date: 5 Jun 89 01:56:49 GMT
Reply-To: adams3@unix.cis.pittsburgh.edu (Larry Adams)
Distribution: usa
Organization: Univ. of Pittsburgh, Comp & Info Sys
Lines: 29

I'm a fairly novice mac programmer; in fact, the program i'm working
on is my first for the mac.  i seem to be having a problem with memory,
and would like the group's collective wisdom.

my program uses a "cursor" based linked list data structure. (no flames
please, it'll be changed to a dynamic structure, but i don't think that'll
affect the problem at hand.)
i initialize it by a call to NewHandle
(i.e., myHndl := structHndl(NewHandle(sizeof(structArray)))  )
the user can then create up to three lists (with windows which would display
them).  i used to pass NIL as the wStorage value, but kept getting the 
THINK pascal error "Address Error".  when i used a variable to store the
windows (actually, an array of three elements, i.e., @wStore[i] ), my
problem went away.
however, when the user has created their three lists ( ==> windows),
i want to put up an alert, saying that they must close one before opening
another.  i'm using StopAlert.  however, i again get "Address Error".
I'm assuming that if i use a dialog & use ModalDialog, then i won't have
the problem, since i can pass a pointer to storage for the dialog window.

my question is, why, when i have ~20 K free memory (as reported by
MemAvail), would i get an address error?  have i done anything
seriously wrong, or overlooked something that should be obvious?

if this is too trivial a question, please send your answer by e-mail.
your help is greatly appreciated, since i'm trying to learn, and i
don't know any mac hackers here at pitt.

	larry adams