Path: utzoo!attcan!utgpu!watmath!iuvax!cica!tut.cis.ohio-state.edu!purdue!bouma
From: bouma@cs.purdue.EDU (William J. Bouma)
Newsgroups: comp.lang.forth
Subject: Re: Toy Forth
Summary: memory management
Keywords: fsh
Message-ID: <8612@medusa.cs.purdue.edu>
Date: 10 Nov 89 17:18:10 GMT
References: <8538@medusa.cs.purdue.edu> <918@acf5.NYU.EDU>
Organization: Department of Computer Science, Purdue University
Lines: 25

In article <918@acf5.NYU.EDU> sabbagh@acf5.UUCP () writes:
>
>I would like to hear more about your efforts.  In particular, how do you
>handle the problem of not knowing how long a word defintion will be usin
>dynamic memory?

   At present my policy is that I should only allocate as much memory as
   is needed. I use adjustable arrays for just about everything internal,
   including the stacks. Thus if a stack overflows I can query the user
   if he wants to grow it. When compiling a word, I begin with an
   array of some default size. If that overflows, I reallocate to a larger
   one. When done I reallocate to just the amount being used. If errors
   occur durring a compile, I free the whole array.

   The only problem with dynamic (de)allocation is the potential for
   memory fragmentation. I am not sure how much of a problem this will be
   in practice? For now, I don't worry about it, and just let the system
   memory manager do what it wants.

   There are other more noticeble changes as well. One can only 'forget'
   individual words and arrays, rather than a word and all that follows it
   in memory. ',' is not useful, so I have found other (better 8^) uses
   for the symbol. 
-- 
Bill <bouma@cs.purdue.edu>  ||  ...!purdue!bouma