Groups > comp.lang.java.programmer > #5194

Re: Call by Result

From	Arved Sandstrom <asandstrom3minus1@eastlink.ca>
Newsgroups	comp.lang.java.programmer
Subject	Re: Call by Result
References	<nkc3v61jg7i21l7n482ce561dq9fdogg3m@4ax.com> <slrniv3i5o.phi.avl@gamma.logic.tuwien.ac.at> <95e4uuF3cvU1@mid.individual.net> <G8nIp.1578$SG4.1543@newsfe03.iad> <slrniv461g.phi.avl@gamma.logic.tuwien.ac.at>
Message-ID	<8CtIp.4644$PA5.4578@newsfe01.iad> (permalink)
Organization	Public Usenet Newsgroup Access
Date	2011-06-10 15:44 -0300

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On 11-06-10 10:12 AM, Andreas Leitgeb wrote:
> Arved Sandstrom <asandstrom3minus1@eastlink.ca> wrote:
>> I'll accept that returning an object containing both the possible
>> modified String and a boolean status is OK. I don't much like it,
> 
> Why would such a returned object contain a possibly *modified* String?
> It would expectably contain whatever String the method getString wants
> the caller to see. It doesn't get one from outside in this case (as 
> opposed to my #2 case), so there's nothing to "modify".

Sorry, my brain disconnected from my fingertips for a few seconds there.
Not "possible modified" String, but just result String. You're quite right.

>> however, for two reasons. It's still the use of a return value for
>> operation status, and although that's defensible, there's nothing OO
>> about it - it's pure imperative programming. And were we to still pursue
>> that approach, unfortunately Java has no elegant means for supporting
>> it, unlike Haskell Maybe or Scala Option.
> 
> Not sure, what feature you're principially talking of.  Is it some kind of 
> syntactic sugar to further simplify code like this:
> 
>   BoolStr bs = getString();
>   boolean b=bs.bool; String s=bs.str;
> 
> ?
> (just curious)

Maybe and Option are datatypes that allow you to return either the
requested value or a value that represents a failure of the computation.
This is conceptually different from having a special value, because in
the case of Maybe or Option, if the function/method succeeds, *every*
possible value of the underlying datatype (String or Integer or
whatever) is still a legal successful value. In effect Maybe and Option
are wrapper types just like BoolStr in your example; it's simply that
Scala and Haskell have better language support for dealing with
datatypes of that sort.

Like I said, in Java the "BoolStr" approach wouldn't be *my* preference
- I like exceptions here. But I wouldn't hold my nose if someone decided
to use "BoolStr".

AHS

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Call by Result Gene Wirchenko <genew@ocis.net> - 2011-06-09 23:03 -0700
  Re: Call by Result Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-06-10 07:33 +0000
    Re: Call by Result Nigel Wade <nmw-news@ion.le.ac.uk> - 2011-06-10 10:03 +0100
      Re: Call by Result Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-06-10 09:47 +0000
      Re: Call by Result Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-06-10 08:23 -0300
        Re: Call by Result Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-06-10 13:12 +0000
          Re: Call by Result Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-06-10 15:44 -0300
            Re: Call by Result Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-06-12 16:29 +0000
              Re: Call by Result Silvio <silvio@moc.com> - 2011-06-12 23:00 +0200
                Re: Call by Result Silvio <silvio@moc.com> - 2011-06-12 23:06 +0200
                Re: Call by Result Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-06-14 10:52 +0000
                Re: Call by Result Silvio <silvio@moc.com> - 2011-06-14 17:13 +0200
                Re: Call by Result Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-06-14 17:58 -0300
                Re: Call by Result Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-06-14 21:18 +0000
                Re: Call by Result Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-06-14 20:14 -0300
                Re: Call by Result Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-06-15 07:13 -0300
                Re: Call by Result Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-06-15 12:50 +0000
                Re: Call by Result Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-06-15 18:52 -0300
                Re: Call by Result lewbloch <lewbloch@gmail.com> - 2011-06-15 07:06 -0700
                Re: Call by Result Michael Wojcik <mwojcik@newsguy.com> - 2011-06-15 21:33 -0400
                Re: Call by Result Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-06-16 11:03 +0000
                Re: Call by Result "H.J. Sander Bruggink" <sander.bruggink@uni-due.de> - 2011-06-16 13:09 +0200
                Re: Call by Result Lewis Bloch <lewisbloch@google.com> - 2011-06-16 06:59 -0700
                Re: Call by Result "John B. Matthews" <nospam@nospam.invalid> - 2011-06-16 23:14 -0400
        Re: Call by Result Gene Wirchenko <genew@ocis.net> - 2011-06-10 11:31 -0700
          Re: Call by Result Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-06-12 14:27 -0300
      Re: Call by Result Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2011-06-10 07:20 -0700
      Re: Call by Result Patricia Shanahan <pats@acm.org> - 2011-06-10 09:30 -0700
        Re: Call by Result Gene Wirchenko <genew@ocis.net> - 2011-06-10 11:44 -0700
    Re: Call by Result Gene Wirchenko <genew@ocis.net> - 2011-06-10 11:26 -0700
      Re: Call by Result Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-06-11 15:07 +0000
        Re: Call by Result Abu Yahya <abu_yahya@invalid.com> - 2011-06-11 23:00 +0530
          Re: Call by Result Martin Gregorie <martin@address-in-sig.invalid> - 2011-06-11 19:36 +0000
            Re: Call by Result Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-06-11 21:06 +0000
              Re: Call by Result Martin Gregorie <martin@address-in-sig.invalid> - 2011-06-12 10:53 +0000
                Re: Call by Result Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2011-06-12 09:28 -0700
                Re: Call by Result Martin Gregorie <martin@address-in-sig.invalid> - 2011-06-12 17:48 +0000
                Re: Call by Result Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2011-06-12 13:19 -0700
            Re: Call by Result Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2011-06-11 15:39 -0700
              Re: Call by Result Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-06-12 11:07 +0000
                Re: Call by Result markspace <-@.> - 2011-06-12 07:02 -0700
                Re: Call by Result Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2011-06-12 09:39 -0700
                Re: Call by Result Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-06-14 10:29 +0000
                Re: Call by Result Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2011-06-14 09:14 -0700
                Re: Call by Result markspace <-@.> - 2011-06-14 09:21 -0700
                Re: Call by Result Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2011-06-14 09:53 -0700
                Re: Call by Result Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2011-06-14 09:57 -0700
            Re: Call by Result Gene Wirchenko <genew@ocis.net> - 2011-06-12 21:44 -0700
        Re: Call by Result Gene Wirchenko <genew@ocis.net> - 2011-06-12 21:40 -0700
  Re: Call by Result Patricia Shanahan <pats@acm.org> - 2011-06-10 01:30 -0700
    Re: Call by Result Gene Wirchenko <genew@ocis.net> - 2011-06-10 11:45 -0700
  Re: Call by Result Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-06-10 07:50 -0400
  Re: Call by Result Silvio <silvio@moc.com> - 2011-06-10 15:35 +0200
  Re: Call by Result Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-06-10 13:56 +0000
  Re: Call by Result Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2011-06-10 07:22 -0700
    Re: Call by Result Gene Wirchenko <genew@ocis.net> - 2011-06-10 11:56 -0700
    Re: Call by Result Gene Wirchenko <genew@ocis.net> - 2011-06-10 11:57 -0700
      Re: Call by Result Patricia Shanahan <pats@acm.org> - 2011-06-10 13:50 -0700
        Re: Call by Result Gene Wirchenko <genew@ocis.net> - 2011-06-12 21:53 -0700
          Re: Call by Result Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-06-13 07:20 -0300
            Re: Call by Result Gene Wirchenko <genew@ocis.net> - 2011-06-13 08:08 -0700
      Re: Call by Result Wojtek <nowhere@a.com> - 2011-06-11 16:35 -0700
        Re: Call by Result Martin Gregorie <martin@address-in-sig.invalid> - 2011-06-12 11:05 +0000
        Re: Call by Result Gene Wirchenko <genew@ocis.net> - 2011-06-12 21:56 -0700
          Re: Call by Result Wojtek <nowhere@a.com> - 2011-06-14 00:40 -0700
    Re: Call by Result Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-06-11 21:18 +0000
  Re: Call by Result markspace <-@.> - 2011-06-10 08:43 -0700
  Re: Call by Result RedGrittyBrick <RedGrittyBrick@spamweary.invalid> - 2011-06-10 17:01 +0100
    Re: Call by Result Martin Gregorie <martin@address-in-sig.invalid> - 2011-06-10 16:55 +0000
    Re: Call by Result Gene Wirchenko <genew@ocis.net> - 2011-06-10 11:59 -0700
      Re: Call by Result Wojtek <nowhere@a.com> - 2011-06-11 16:24 -0700
        Re: Call by Result Gene Wirchenko <genew@ocis.net> - 2011-06-12 21:59 -0700
          Re: Call by Result Paul Cager <paul.cager@googlemail.com> - 2011-06-13 07:53 -0700
          Re: Call by Result Wojtek <nowhere@a.com> - 2011-06-14 00:43 -0700
  Re: Call by Result Gene Wirchenko <genew@ocis.net> - 2011-06-10 11:55 -0700
  Re: Call by Result Steven Simpson <ss@domain.invalid> - 2011-06-11 09:09 +0100
  Re: Call by Result Cholo Lennon <chololennon@hotmail.com> - 2011-06-16 11:30 -0300
    Re: Call by Result Paul Cager <paul.cager@googlemail.com> - 2011-06-17 02:38 -0700
      Re: Call by Result Gene Wirchenko <genew@ocis.net> - 2011-06-17 12:06 -0700
    Re: Call by Result lewbloch <lewbloch@gmail.com> - 2011-06-17 06:40 -0700
      Re: Call by Result Cholo Lennon <chololennon@hotmail.com> - 2011-06-17 11:43 -0300

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