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Re: Region-based dynamic memory management idea

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On Tue, 10 Jun 2014 12:50:32 -0400, Anton Ertl  
<anton@mips.complang.tuwien.ac.at> wrote:
> "Rod Pemberton" <dont_use_email@xnothavet.cqm> writes:
>> On Sun, 08 Jun 2014 11:05:36 -0400, Anton Ertl
>> <anton@mips.complang.tuwien.ac.at> wrote:

>>> str+ ( c-addr1 u1 c-addr2 u2 -- c-addr3 u3 )
>>> It has to allocate memory for the result.
>>
>> Wow, that really looks like the C way of string concatenation to me ...
>
> Really?  *The* C way of string concatenation is strcat(), and a Forth
> stack effect for that function would be:
>
> ( dest src -- dest )
>
> where dest and src represent zero-terminated strings.

Yes, you must disregard the termination method to compare the two.
So, we drop the length from Forth:

str+ ( c-addr1 c-addr2 -- c-addr3 )

Now, they look much closer.

If c-addr1 is sufficiently large, then c-addr1 could be equal to
c-addr3, i.e., no allocation required.

str+ ( dest src -- dest )

In which case, they're now equal except for termination.

Of course, Forth complicates string termination, so we must provide
additional information to the Forth word, re-complicating things:

str+ ( dest u1 src u2 -- dest u3 )

> I think you
> could not get much farther from STR+ than with strcat(), and still
> have a string concatenation word/function.

They're both concatenation, so they're closer than not ...

> In particular and relevant
> to the original topic, STR+ allocates memory, and strcat does not.

So, STR+ is not identical and comprises roughly about five C function
calls ... 2 strlen's, 1 malloc, 1 strcpy, 1 strcat and some miscellaneous
arithmetic. It's still much closer to the C way of doing things.  The
point was it doesn't appear to be the Forth way.  The Forth way would
be colon definitions or some manipulation of the parser and/or writing
into the input stream/buffer to use ." to define the concatenated string.

>> I'm not
>> sure how you'd go about freeing and re-using the space for the
>> original two strings.
>
> Than maybe you should give up on C and convert to Java.

You snipped so much, I think you replied to something else here...

I was talking about the space already allocated in a typical Forth
dictionary for "c-addr1 u1" and "c-addr2 u2".  AFAIK, using the
standard HERE DP ALLOT Forth mechanism, there is no way in Forth to
reclaim just the space for those two strings.  Those two strings
will be packed inbetween other Forth words.  So, you'd need extra
functionality, i.e., a garbage collector or paging, to reclaim the
space.  So, without the ability to reclaim that space, the best you
can do is add another string to the dictionary, i.e., "c-addr3 u3",
causing additional consumption of stack space, which could be
considered a memory leak.

> Or do you
> know how you free and reuse the src operand when using strcat()?

It's not needed.  As you pointed out, C's allocation and concatenation
mechanisms are purely separate.  I.e., the src operand is assumed
to be sufficiently large than strcat can safely append.  It's the
programmer's job to make sure that it is large enough.  Of course,
some programmers fail to take care of the details in C, which is also
a strong argument against using Forth.  If you were to do the same
thing in Forth using STR+, i.e., extra large allocation for "c-addr1 u1",
then I'd claim that's even stronger support that you've embraced the
C way.


Rod Pemberton

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Thread

Region-based dynamic memory management idea Roger Levy <roger.levy@gmail.com> - 2014-06-07 23:35 -0700
  Re: Region-based dynamic memory management idea Mark Wills <markwills1970@gmail.com> - 2014-06-08 03:20 -0700
    Re: Region-based dynamic memory management idea Mark Wills <markwills1970@gmail.com> - 2014-06-08 03:39 -0700
  Re: Region-based dynamic memory management idea anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-06-08 13:23 +0000
    Re: Region-based dynamic memory management idea Roger Levy <roger.levy@gmail.com> - 2014-06-08 07:44 -0700
      Re: Region-based dynamic memory management idea anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-06-08 15:05 +0000
        Re: Region-based dynamic memory management idea Roger Levy <roger.levy@gmail.com> - 2014-06-08 09:01 -0700
          Re: Region-based dynamic memory management idea Roger Levy <roger.levy@gmail.com> - 2014-06-08 09:32 -0700
            Re: Region-based dynamic memory management idea Mark Wills <markwills1970@gmail.com> - 2014-06-08 10:08 -0700
              Re: Region-based dynamic memory management idea Roger Levy <roger.levy@gmail.com> - 2014-06-08 21:05 -0700
                Re: Region-based dynamic memory management idea Mark Wills <markwills1970@gmail.com> - 2014-06-09 06:47 -0700
              Re: Region-based dynamic memory management idea Alexander Skobelev <al.skobelev@gmail.com> - 2014-06-09 08:27 +0400
                Re: Region-based dynamic memory management idea Roger Levy <roger.levy@gmail.com> - 2014-06-08 22:42 -0700
                Re: Region-based dynamic memory management idea Mark Wills <markwills1970@gmail.com> - 2014-06-09 06:53 -0700
                Re: Region-based dynamic memory management idea Alexander Skobelev <al.skobelev@gmail.com> - 2014-06-10 09:24 +0400
          Re: Region-based dynamic memory management idea anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-06-09 14:55 +0000
        Re: Region-based dynamic memory management idea "Rod Pemberton" <dont_use_email@xnothavet.cqm> - 2014-06-08 21:10 -0400
          Re: Region-based dynamic memory management idea "Elizabeth D. Rather" <erather@forth.com> - 2014-06-08 16:55 -1000
          Re: Region-based dynamic memory management idea visualforth@rocketmail.com - 2014-06-08 20:34 -0700
            Re: Region-based dynamic memory management idea "Elizabeth D. Rather" <erather@forth.com> - 2014-06-08 18:55 -1000
              Re: Region-based dynamic memory management idea Roger Levy <roger.levy@gmail.com> - 2014-06-08 22:50 -0700
                Re: Region-based dynamic memory management idea "Elizabeth D. Rather" <erather@forth.com> - 2014-06-09 12:54 -1000
                Re: Region-based dynamic memory management idea Roger Levy <roger.levy@gmail.com> - 2014-06-09 17:33 -0700
                Re: Region-based dynamic memory management idea Andrew Haley <andrew29@littlepinkcloud.invalid> - 2014-06-10 04:37 -0500
                Re: Region-based dynamic memory management idea bruce.mcfarling@gmail.com - 2014-06-19 13:38 -0700
              Re: Region-based dynamic memory management idea albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-06-09 12:40 +0000
          Re: Region-based dynamic memory management idea Andrew Haley <andrew29@littlepinkcloud.invalid> - 2014-06-09 05:21 -0500
          Re: Region-based dynamic memory management idea anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-06-10 16:50 +0000
            Re: Region-based dynamic memory management idea "Rod Pemberton" <dont_use_email@xnothavet.cqm> - 2014-06-10 17:36 -0400
            Re: Region-based dynamic memory management idea bruce.mcfarling@gmail.com - 2014-06-14 09:52 -0700
        Re: Region-based dynamic memory management idea humptydumpty <ouatubi@gmail.com> - 2014-06-11 03:44 -0700
          Re: Region-based dynamic memory management idea anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-06-11 16:33 +0000
            Re: Region-based dynamic memory management idea humptydumpty <ouatubi@gmail.com> - 2014-06-12 14:01 -0700
              Re: Region-based dynamic memory management idea anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-06-13 16:42 +0000
                Re: Region-based dynamic memory management idea humptydumpty <ouatubi@gmail.com> - 2014-06-13 13:45 -0700
                Re: Region-based dynamic memory management idea anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-06-14 09:56 +0000
                Re: Region-based dynamic memory management idea humptydumpty <ouatubi@gmail.com> - 2014-06-14 06:29 -0700
                Re: Region-based dynamic memory management idea Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2014-06-16 00:19 +0100
    Re: Region-based dynamic memory management idea Bernd Paysan <bernd.paysan@gmx.de> - 2014-06-08 21:47 +0200
      Re: Region-based dynamic memory management idea anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-06-09 15:24 +0000
        Re: Region-based dynamic memory management idea Mark Wills <markwills1970@gmail.com> - 2014-06-09 09:10 -0700
          Re: Region-based dynamic memory management idea anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-06-10 16:09 +0000
            Re: Region-based dynamic memory management idea BruceMcF <agila61@netscape.net> - 2014-06-14 14:04 -0700
        Re: Region-based dynamic memory management idea Roger Levy <roger.levy@gmail.com> - 2014-06-09 10:02 -0700
          Re: Region-based dynamic memory management idea Roger Levy <roger.levy@gmail.com> - 2014-06-09 10:08 -0700
            Re: Region-based dynamic memory management idea anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-06-10 15:31 +0000
              Re: Region-based dynamic memory management idea BruceMcF <agila61@netscape.net> - 2014-06-14 13:27 -0700
          Re: Region-based dynamic memory management idea anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-06-10 15:51 +0000
        Re: Region-based dynamic memory management idea bruce.mcfarling@gmail.com - 2014-06-14 09:09 -0700
          Re: Region-based dynamic memory management idea mhx@iae.nl - 2014-06-14 09:49 -0700
            Re: Region-based dynamic memory management idea bruce.mcfarling@gmail.com - 2014-06-14 10:09 -0700
            Re: Region-based dynamic memory management idea albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-06-14 19:36 +0000
              Re: Region-based dynamic memory management idea mhx@iae.nl - 2014-06-14 23:06 -0700
                Re: Region-based dynamic memory management idea albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-06-15 12:33 +0000
                Re: Region-based dynamic memory management idea BruceMcF <agila61@netscape.net> - 2014-06-15 12:11 -0700
                Re: Region-based dynamic memory management idea albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-06-15 19:38 +0000
  Re: Region-based dynamic memory management idea visualforth@rocketmail.com - 2014-06-08 17:42 -0700
    Re: Region-based dynamic memory management idea anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2014-06-09 15:43 +0000
    Re: Region-based dynamic memory management idea BruceMcF <agila61@netscape.net> - 2014-06-14 13:08 -0700
      Re: Region-based dynamic memory management idea "Elizabeth D. Rather" <erather@forth.com> - 2014-06-14 11:54 -1000
        Re: Region-based dynamic memory management idea BruceMcF <agila61@netscape.net> - 2014-06-15 12:36 -0700
      Re: Region-based dynamic memory management idea albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-06-15 11:59 +0000
        Re: Region-based dynamic memory management idea BruceMcF <agila61@netscape.net> - 2014-06-15 12:55 -0700
          Re: Region-based dynamic memory management idea BruceMcF <agila61@netscape.net> - 2014-06-15 13:02 -0700
  Re: Region-based dynamic memory management idea Roger Levy <roger.levy@gmail.com> - 2014-06-12 10:26 -0700
  Re: Region-based dynamic memory management idea Roger Levy <roger.levy@gmail.com> - 2014-06-19 22:57 -0700
    Re: Region-based dynamic memory management idea Mark Wills <markwills1970@gmail.com> - 2014-06-20 07:40 +0100
      Re: Region-based dynamic memory management idea Roger Levy <roger.levy@gmail.com> - 2014-06-20 00:14 -0700
        Re: Region-based dynamic memory management idea bruce.mcfarling@gmail.com - 2014-06-20 20:17 -0700
          Re: Region-based dynamic memory management idea Roger Levy <roger.levy@gmail.com> - 2014-06-21 08:51 -0700
            Re: Region-based dynamic memory management idea bruce.mcfarling@gmail.com - 2014-06-21 10:07 -0700
              Re: Region-based dynamic memory management idea Roger Levy <roger.levy@gmail.com> - 2014-06-21 11:10 -0700
                Re: Region-based dynamic memory management idea bruce.mcfarling@gmail.com - 2014-06-21 12:17 -0700
                Re: Region-based dynamic memory management idea Roger Levy <roger.levy@gmail.com> - 2014-06-21 12:39 -0700
                Re: Region-based dynamic memory management idea bruce.mcfarling@gmail.com - 2014-06-21 13:54 -0700
                Re: Region-based dynamic memory management idea Roger Levy <roger.levy@gmail.com> - 2014-06-21 14:53 -0700
                Re: Region-based dynamic memory management idea albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-06-22 13:58 +0000
                Re: Region-based dynamic memory management idea BruceMcF <agila61@netscape.net> - 2014-06-22 15:26 -0700
  Re: Region-based dynamic memory management idea Roger Levy <roger.levy@gmail.com> - 2014-06-21 13:25 -0700
  Re: Region-based dynamic memory management idea Roger Levy <roger.levy@gmail.com> - 2014-06-25 14:55 -0700

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