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From: alistair@minster.york.ac.uk
Newsgroups: comp.sys.mac.programmer
Subject: Object Pascal and memory management
Message-ID: <604330910.18716@minster.york.ac.uk>
Date: 24 Feb 89 13:41:50 GMT
Organization: Department of Computer Science, University of York, England
Lines: 38

Can anyone out there explain how Object Pascal objects are allocated in memory,
and the relationship to segementation?  I have a program which sometimes bombs
due, I suspect to memory problems.  I should say that I am NOT using MacApp.

An object is a handle, right.  So when if write:

type
  Tthing = object(Tobject)
		i : integer;
		procedure p;
			...
	   end;
{$S seg1}
procedure Tthing.p;
...
{$S seg2}

var
  thing : Tthing;
begin
  new(thing) 

New allocates some memory on the heap and thing is set as an indirect pointer to it.
What goes in that bit of memory: the code for Tthing (i.e. for Tthing.p) and/or space
for the instance variable i?  What if I call new for another Tthing object?  Surely
I don't need another copy of the code for Tthing.p, but do I get one anyway?  What
does dispose(thing) do?

And then... I have had to segment my program because the compiler began to complain
about segments >32K, but what does that mean in the context of objects?  Can I
unload a segment I have finished with by something like UnloadSeg(@thing.p) -
and what would it mean if I did? How would that work in relation to a dispose(thing)?

I hope someone out there is able and willing to help.  I did try getting the
answers from the Apple Developers' Group - the British version of APDA - and
they knew no more than me, and couldn't be bothered finding out.  As far as
I'm concerned they are a waste of time and I don't care who knows it.  (These
are - of course - NOT necessarily the views of my employers, blah blah blah)