Groups > comp.lang.java.programmer > #13733

Re: no more primitive data types in Java (JDK 10+). What do you think?

From	BGB <cr88192@hotmail.com>
Newsgroups	comp.lang.java.programmer
Subject	Re: no more primitive data types in Java (JDK 10+). What do you think?
Date	2012-04-20 20:47 -0700
Organization	albasani.net
Message-ID	<jmtanb$q1e$1@news.albasani.net> (permalink)
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On 4/20/2012 6:45 AM, Robert Klemme wrote:
> On 04/20/2012 02:31 AM, Lew wrote:
>
>> There's also the point that source distinctions might look different
>> in bytecode or machine code. What we might think of as an 'int' object
>> at the source level might be treated as an ordinary machine integer at
>> the lower level.
>
> As an additional data point: Ruby MRI works like that. Basically
> integers (instances of class Fixnum) look like ordinary objects but
> under the hood the value is encoded in the reference and there is no
> object on the heap. You get a nice consistent model for the language
> user but avoid the overhead of GC. Ruby is still not a racing car
> compared with other PL - usual trade offs apply. The concept is
> described here:
> http://en.wikipedia.org/wiki/Tagged_pointer
>
> It could require a signicifant (nice typo, sounds like an animal) change
> in the JVM definition though.
>

AFAIK, in development versions of the JVM this is apparently already 
being worked on (I remember seeing it being talked about a few months 
back on one of the JVM development mailing lists). I am not really sure 
about the implementation specifics though.

my own VM also has fixnums, although they don't use tagged pointers.

the VM uses inaccessible address-ranges as types.

on 32-bit x86 targets, this generally means the space between 0xC0000000 
and 0xFFFFFFFF. on x86-64, a much bigger chunk of address space is used 
(currently a roughly 56-bit wide region, but on current HW this could be 
pushed actually to about 60 or 62 bits, given the actual accessible part 
of the space is relatively tiny).

as-is, this currently means 28 bit fixnums on x86, and 48 bit fixnums on 
x86-64, rather than the 30 and 62 bits possible via tagged pointers.

an advantage, however, is that this does not interfere with my ability 
to make use of unaligned pointers: I wanted a system where I could point 
a character pointer anywhere in a string, and still have the 
type-checking able to figure out that it was a string, and more so, also 
be able to tell me the address of the start of the string and the 
relative offset therein.

it all works fairly well, although type-checking is potentially a little 
more costly, given that most such operations need to identify the base 
of the heap-object in question. luckily, these lookups are 
"approximately" constant time (it is not really constant, but roughly 
ranges from O(1) to O(log2 n) depending on various factors).

or such...

Thread

no more primitive data types in Java (JDK 10+). What do you think? "Nasser M. Abbasi" <nma@12000.org> - 2012-04-19 18:27 -0500
  Re: no more primitive data types in Java (JDK 10+). What do you think? Arne Vajhøj <arne@vajhoej.dk> - 2012-04-19 20:02 -0400
    Re: no more primitive data types in Java (JDK 10+). What do you think? Lew <lewbloch@gmail.com> - 2012-04-19 17:31 -0700
      Re: no more primitive data types in Java (JDK 10+). What do you think? Robert Klemme <shortcutter@googlemail.com> - 2012-04-20 15:45 +0200
        Re: no more primitive data types in Java (JDK 10+). What do you think? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-04-20 15:05 +0000
          Re: no more primitive data types in Java (JDK 10+). What do you think? Robert Klemme <shortcutter@googlemail.com> - 2012-04-20 19:32 +0200
        Re: no more primitive data types in Java (JDK 10+). What do you think? BGB <cr88192@hotmail.com> - 2012-04-20 20:47 -0700
    Re: no more primitive data types in Java (JDK 10+). What do you think? Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2012-04-19 17:45 -0700
      Re: no more primitive data types in Java (JDK 10+). What do you think? Arne Vajhøj <arne@vajhoej.dk> - 2012-04-19 21:22 -0400
      Re: no more primitive data types in Java (JDK 10+). What do you think? "Nasser M. Abbasi" <nma@12000.org> - 2012-04-19 21:16 -0500
        Re: no more primitive data types in Java (JDK 10+). What do you think? Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2012-04-19 23:11 -0700
  Re: no more primitive data types in Java (JDK 10+). What do you think? Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-04-19 21:35 -0300
    Re: no more primitive data types in Java (JDK 10+). What do you think? Arne Vajhøj <arne@vajhoej.dk> - 2012-04-19 21:31 -0400
    Re: no more primitive data types in Java (JDK 10+). What do you think? Lew <lewbloch@gmail.com> - 2012-04-19 19:22 -0700
      Re: no more primitive data types in Java (JDK 10+). What do you think? Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2012-04-19 23:15 -0700
        Re: no more primitive data types in Java (JDK 10+). What do you think? BGB <cr88192@hotmail.com> - 2012-04-20 07:45 -0700
          Re: no more primitive data types in Java (JDK 10+). What do you think? Lew <noone@lewscanon.com> - 2012-04-20 08:20 -0700
            Re: no more primitive data types in Java (JDK 10+). What do you think? BGB <cr88192@hotmail.com> - 2012-04-20 19:57 -0700
              Re: no more primitive data types in Java (JDK 10+). What do you think? Lew <noone@lewscanon.com> - 2012-04-21 04:25 -0700
                Re: no more primitive data types in Java (JDK 10+). What do you think? Leif Roar Moldskred <leifm@dimnakorr.com> - 2012-04-21 07:05 -0500
                Re: no more primitive data types in Java (JDK 10+). What do you think? BGB <cr88192@hotmail.com> - 2012-04-21 07:42 -0700
                Re: no more primitive data types in Java (JDK 10+). What do you think? Lew <noone@lewscanon.com> - 2012-04-21 12:55 -0700
                Re: no more primitive data types in Java (JDK 10+). What do you think? BGB <cr88192@hotmail.com> - 2012-04-21 13:27 -0700
                Re: no more primitive data types in Java (JDK 10+). What do you think? Lew <noone@lewscanon.com> - 2012-04-21 13:34 -0700
                Re: no more primitive data types in Java (JDK 10+). What do you think? BGB <cr88192@hotmail.com> - 2012-04-21 14:01 -0700
                Re: no more primitive data types in Java (JDK 10+). What do you think? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-04-21 23:48 +0000
                Re: no more primitive data types in Java (JDK 10+). What do you think? Lew <noone@lewscanon.com> - 2012-04-21 17:46 -0700
        Re: no more primitive data types in Java (JDK 10+). What do you think? Gene Wirchenko <genew@ocis.net> - 2012-04-20 08:08 -0700
          Re: no more primitive data types in Java (JDK 10+). What do you think? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-04-20 16:46 +0000
            Re: no more primitive data types in Java (JDK 10+). What do you think? Lew <lewbloch@gmail.com> - 2012-04-20 12:52 -0700
        Re: no more primitive data types in Java (JDK 10+). What do you think? Lew <noone@lewscanon.com> - 2012-04-20 08:17 -0700
          Re: no more primitive data types in Java (JDK 10+). What do you think? Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2012-04-20 09:02 -0700
            Re: no more primitive data types in Java (JDK 10+). What do you think? Lew <lewbloch@gmail.com> - 2012-04-20 12:48 -0700
            Re: no more primitive data types in Java (JDK 10+). What do you think? David Lamb <dalamb@cs.queensu.ca> - 2012-04-20 21:08 -0400
              Re: no more primitive data types in Java (JDK 10+). What do you think? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-04-21 01:55 +0000
                Re: no more primitive data types in Java (JDK 10+). What do you think? Lew <noone@lewscanon.com> - 2012-04-21 04:28 -0700
  Re: no more primitive data types in Java (JDK 10+). What do you think? Joshua Cranmer <Pidgeot18@verizon.invalid> - 2012-04-19 19:36 -0500
  Re: no more primitive data types in Java (JDK 10+). What do you think? Tsukino Usagi <usagi@tsukino.ca> - 2012-04-20 15:27 +0900
    Re: no more primitive data types in Java (JDK 10+). What do you think? Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-04-20 07:04 -0300
      Re: no more primitive data types in Java (JDK 10+). What do you think? Tsukino Usagi <usagi@tsukino.ca> - 2012-04-20 22:17 +0900
        Re: no more primitive data types in Java (JDK 10+). What do you think? Robert Klemme <shortcutter@googlemail.com> - 2012-04-20 15:59 +0200
      Re: no more primitive data types in Java (JDK 10+). What do you think? Thufir <hawat.thufir@gmail.com> - 2012-04-20 14:21 -0700
      Re: no more primitive data types in Java (JDK 10+). What do you think? Arne Vajhøj <arne@vajhoej.dk> - 2012-04-20 19:11 -0400
    Re: no more primitive data types in Java (JDK 10+). What do you think? Tsukino Usagi <usagi@tsukino.ca> - 2012-04-20 22:16 +0900
      Re: no more primitive data types in Java (JDK 10+). What do you think? Robert Klemme <shortcutter@googlemail.com> - 2012-04-20 15:55 +0200
    Re: no more primitive data types in Java (JDK 10+). What do you think? Patricia Shanahan <pats@acm.org> - 2012-04-20 07:49 -0700
      Re: no more primitive data types in Java (JDK 10+). What do you think? Arne Vajhøj <arne@vajhoej.dk> - 2012-04-20 19:19 -0400
        Re: no more primitive data types in Java (JDK 10+). What do you think? BGB <cr88192@hotmail.com> - 2012-04-21 07:58 -0700
    Re: no more primitive data types in Java (JDK 10+). What do you think? rossum <rossum48@coldmail.com> - 2012-04-20 20:08 +0100
      Re: no more primitive data types in Java (JDK 10+). What do you think? Lew <lewbloch@gmail.com> - 2012-04-20 12:54 -0700
        Re: no more primitive data types in Java (JDK 10+). What do you think? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-04-20 21:48 +0000
          Re: no more primitive data types in Java (JDK 10+). What do you think? Lew <lewbloch@gmail.com> - 2012-04-20 16:45 -0700
            Re: no more primitive data types in Java (JDK 10+). What do you think? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2012-04-21 01:56 +0000
              Re: no more primitive data types in Java (JDK 10+). What do you think? Lew <noone@lewscanon.com> - 2012-04-21 04:35 -0700
      Re: no more primitive data types in Java (JDK 10+). What do you think? Jim Janney <jjanney@shell.xmission.com> - 2012-04-20 16:24 -0600
    Re: no more primitive data types in Java (JDK 10+). What do you think? Arne Vajhøj <arne@vajhoej.dk> - 2012-04-20 19:08 -0400
    Re: no more primitive data types in Java (JDK 10+). What do you think? Joshua Cranmer <Pidgeot18@verizon.invalid> - 2012-04-20 18:14 -0500
      Re: no more primitive data types in Java (JDK 10+). What do you think? Arne Vajhøj <arne@vajhoej.dk> - 2012-04-20 19:22 -0400
      Re: no more primitive data types in Java (JDK 10+). What do you think? Arne Vajhøj <arne@vajhoej.dk> - 2012-04-20 20:36 -0400
  Re: no more primitive data types in Java (JDK 10+). What do you think? Roedy Green <see_website@mindprod.com.invalid> - 2012-04-20 05:33 -0700
    Re: no more primitive data types in Java (JDK 10+). What do you think? Bernd Nawothnig <Bernd.Nawothnig@t-online.de> - 2012-04-20 20:53 +0200
      Re: no more primitive data types in Java (JDK 10+). What do you think? Gene Wirchenko <genew@ocis.net> - 2012-04-20 13:36 -0700
        Re: no more primitive data types in Java (JDK 10+). What do you think? Bernd Nawothnig <Bernd.Nawothnig@t-online.de> - 2012-04-21 10:20 +0200
          Re: no more primitive data types in Java (JDK 10+). What do you think? Gene Wirchenko <genew@ocis.net> - 2012-04-23 10:24 -0700
            Re: no more primitive data types in Java (JDK 10+). What do you think? BGB <cr88192@hotmail.com> - 2012-04-24 14:39 -0700
              Re: no more primitive data types in Java (JDK 10+). What do you think? Lew <lewbloch@gmail.com> - 2012-04-24 15:06 -0700
                Re: no more primitive data types in Java (JDK 10+). What do you think? BGB <cr88192@hotmail.com> - 2012-04-24 17:07 -0700
                Re: no more primitive data types in Java (JDK 10+). What do you think? Lew <noone@lewscanon.com> - 2012-04-25 00:48 -0700
                Re: no more primitive data types in Java (JDK 10+). What do you think? BGB <cr88192@hotmail.com> - 2012-04-25 08:20 -0700
                Re: no more primitive data types in Java (JDK 10+). What do you think? Lew <noone@lewscanon.com> - 2012-04-25 08:59 -0700
                Re: no more primitive data types in Java (JDK 10+). What do you think? BGB <cr88192@hotmail.com> - 2012-04-25 10:32 -0700
              Re: no more primitive data types in Java (JDK 10+). What do you think? Tsukino Usagi <usagi@tsukino.ca> - 2012-04-29 23:03 +0900
                Re: no more primitive data types in Java (JDK 10+). What do you think? BGB <cr88192@hotmail.com> - 2012-04-29 10:28 -0700
      Re: no more primitive data types in Java (JDK 10+). What do you think? BGB <cr88192@hotmail.com> - 2012-04-21 08:55 -0700
        Re: no more primitive data types in Java (JDK 10+). What do you think? Lew <noone@lewscanon.com> - 2012-04-21 12:56 -0700
          Re: no more primitive data types in Java (JDK 10+). What do you think? BGB <cr88192@hotmail.com> - 2012-04-21 13:41 -0700
  Re: no more primitive data types in Java (JDK 10+). What do you think? Silvio Bierman <silvio@moc.com> - 2012-04-20 16:50 +0200
    Re: no more primitive data types in Java (JDK 10+). What do you think? Arne Vajhøj <arne@vajhoej.dk> - 2012-04-20 19:04 -0400

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