Groups > comp.lang.java.programmer > #30205

Re: redesign exception

Newsgroups	comp.lang.java.programmer
Date	2014-10-27 07:01 -0700
References	<c79cbd2e-970b-4cd3-b181-da33bb43c4b6@googlegroups.com> <544dfc54$0$2842$e4fe514c@news.xs4all.nl> <9c03f8fd-587e-4112-ad08-6d10017ebe0b@googlegroups.com> <544e3b57$0$2922$e4fe514c@news.xs4all.nl>
Message-ID	<e02b0706-3d31-4136-9763-06b4ba71dec8@googlegroups.com> (permalink)
Subject	Re: redesign exception
From	boxzou@gmail.com

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> case SQLException(14) => println("SQL error 14")
This is very close to what I want.  It would be better if we don't have to write any extractor at all.

Fault(FaultCode code, String...args): args is varargs, the length is validated against numArgs in FaultCode.
FaultCode(String code, int numArgs, String messageTemplate).

Scala is a very interesting language.  Competition drives innovation.

Thanks.

On Monday, 27 October 2014 08:32:32 UTC-4, Silvio  wrote:
> Were SQLException a Scala case class or would someone add an extractor 
> after the fact (which you can easily do yourself without breaking 
> anything) that would become:
> 
> case SQLException(14) => println("SQL error 14")
> case SQLException(15) => println("SQL error 15")
> case SQLException(x) => println("SQL errror " + x)
> 
> where the latter would match any SQL exception extracting the number into x.
> 
> This is all about language, nothing else. Standardization on exception 
> will not happen simply because there is no fixed format to catch all 
> imaginable types of exceptions in. Exceptions in general can not be 
> brought down to 1, 2 or any n fixed fields or values.
> 
> A language like Scala however, allows you to write such extractors for 
> any given set of exception types that are relevant to your code.
> 
> A language designed for extensibility allows you to define this without 
> having to change the language itself. Among others Scala is such a 
> language, Java is not. Pattern matching is just an example but there is 
> plenty more.
> 
> 
> On 10/27/2014 01:06 PM, box...@gmail.com wrote:
> > What I'd really like to achieve is to be able to say:
> >
> > case x : java.sql.SQLException.14
> >
> > Language does not matter.  The problem I posted about is across all OO languages.
> >
> > Other points:
> > 1. standardize the details as parameters
> > 2. documentation and I18N support through messageTemplate.
> >
> > The new exception handling mechanism can be added in a backward compatible manner so nothing would be broken.
> >
> > The current way one public class per  Java file has its advantage:  so easy to search for a class.
> >
> > On Monday, 27 October 2014 04:03:43 UTC-4, Silvio  wrote:
> >> Simply switch to Scala's exception syntax and most of your problem goes
> >> away:
> >>
> >> try
> >> {
> >>      // something dangerous
> >> }
> >> catch
> >> {
> >>      case x : java.sql.SQLException if x.getErrorCode() == 14 => // SQL 14
> >>      case x : Exception => println(x.getMessage)
> >> }
> >>
> >> Scala extends its pattern matching syntax to handle exceptions. If you
> >> define your user exceptions as case classes (special type of class that
> >> automagically has extended support for pattern matching) you can not
> >> only catch cases based on class and an if-clause but specify any pattern
> >> that Scala pattern matching supports.
> >>
> >> This not only allows more fine-grained handling but also enables you to
> >> extract exception fields/details while matching. Too much to summarize
> >> here, I suggest you look into Scala pattern matching.
> >>
> >> Oh, and in Scala you can put as many classes in a source as you want.
> >> That might be a nice change to Java as well...
> >>
> >> Then again, as a variation on a common saying: if it's too much broken
> >> don't fix it...
> >>

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Thread

redesign exception boxzou@gmail.com - 2014-10-25 19:16 -0700
  Re: redesign exception Joerg Meier <joergmmeier@arcor.de> - 2014-10-26 08:09 +0100
    Re: redesign exception rossum <rossum48@coldmail.com> - 2014-10-26 09:15 +0000
      Re: redesign exception Joerg Meier <joergmmeier@arcor.de> - 2014-10-26 10:36 +0100
      Re: redesign exception Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-10-26 09:23 -0400
        Re: redesign exception boxzou@gmail.com - 2014-10-26 12:56 -0700
          Re: redesign exception Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-10-26 18:10 -0400
            Re: redesign exception boxzou@gmail.com - 2014-10-26 17:39 -0700
      Re: redesign exception boxzou@gmail.com - 2014-10-26 12:06 -0700
        Re: redesign exception Joerg Meier <joergmmeier@arcor.de> - 2014-10-26 20:41 +0100
    Re: redesign exception boxzou@gmail.com - 2014-10-26 12:46 -0700
      Re: redesign exception boxzou@gmail.com - 2014-10-26 13:12 -0700
      Re: redesign exception Leif Roar Moldskred <leifm@huldreskog.localdomain> - 2014-10-26 16:50 -0500
        Re: redesign exception boxzou@gmail.com - 2014-10-26 17:21 -0700
      Re: redesign exception Martin Gregorie <martin@address-in-sig.invalid> - 2014-10-27 01:05 +0000
        Re: redesign exception boxzou@gmail.com - 2014-10-26 19:38 -0700
          Re: redesign exception Leif Roar Moldskred <leifm@huldreskog.localdomain> - 2014-10-27 00:13 -0500
            Re: redesign exception boxzou@gmail.com - 2014-10-27 04:59 -0700
            Re: redesign exception Marketa Jadalova <m-jadalova3@gmail.com> - 2014-10-27 16:55 +0000
              Re: redesign exception Leif Roar Moldskred <leifm@huldreskog.localdomain> - 2014-10-27 12:46 -0500
                Re: redesign exception boxzou@gmail.com - 2014-10-27 15:48 -0700
                Re: redesign exception Leif Roar Moldskred <leifm@huldreskog.localdomain> - 2014-10-27 22:16 -0500
                Re: redesign exception Robert Klemme <shortcutter@googlemail.com> - 2014-10-27 23:54 +0100
                Re: redesign exception boxzou@gmail.com - 2014-10-27 17:20 -0700
                Re: redesign exception boxzou@gmail.com - 2014-10-28 07:12 -0700
                Re: redesign exception Robert Klemme <shortcutter@googlemail.com> - 2014-10-29 08:34 +0100
                Re: redesign exception Martin Gregorie <martin@address-in-sig.invalid> - 2014-10-29 11:17 +0000
                Re: redesign exception Silvio <silvio@internet.com> - 2014-10-29 15:33 +0100
                Re: redesign exception Leif Roar Moldskred <leifm@huldreskog.localdomain> - 2014-10-29 11:35 -0500
                Re: redesign exception boxzou@gmail.com - 2014-10-29 17:51 -0700
                Re: redesign exception Leif Roar Moldskred <leifm@huldreskog.localdomain> - 2014-10-29 20:45 -0500
                Re: redesign exception boxzou@gmail.com - 2014-10-30 04:12 -0700
                Re: redesign exception Silvio <silvio@internet.com> - 2014-10-30 12:38 +0100
                Re: redesign exception boxzou@gmail.com - 2014-10-30 06:23 -0700
                Re: redesign exception boxzou@gmail.com - 2014-10-29 17:01 -0700
                Re: redesign exception Marketa Jadalova <m-jadalova3@gmail.com> - 2014-10-29 16:55 +0000
                Re: redesign exception Martin Gregorie <martin@address-in-sig.invalid> - 2014-10-29 17:29 +0000
                Re: redesign exception Robert Klemme <shortcutter@googlemail.com> - 2014-10-29 18:59 +0100
                Re: redesign exception Martin Gregorie <martin@address-in-sig.invalid> - 2014-10-29 22:05 +0000
                Re: redesign exception boxzou@gmail.com - 2014-10-29 18:04 -0700
                Re: redesign exception Leif Roar Moldskred <leifm@huldreskog.localdomain> - 2014-10-29 20:56 -0500
                Re: redesign exception boxzou@gmail.com - 2014-10-30 04:19 -0700
                Re: redesign exception boxzou@gmail.com - 2014-10-30 04:27 -0700
                Re: redesign exception boxzou@gmail.com - 2014-10-30 04:35 -0700
                Re: redesign exception boxzou@gmail.com - 2014-10-29 18:01 -0700
                Re: redesign exception boxzou@gmail.com - 2014-10-29 17:00 -0700
                Re: redesign exception boxzou@gmail.com - 2014-10-29 16:56 -0700
    Re: redesign exception boxzou@gmail.com - 2014-10-26 12:52 -0700
  Re: redesign exception Silvio <silvio@internet.com> - 2014-10-27 09:03 +0100
    Re: redesign exception boxzou@gmail.com - 2014-10-27 05:06 -0700
      Re: redesign exception Silvio <silvio@internet.com> - 2014-10-27 13:32 +0100
        Re: redesign exception boxzou@gmail.com - 2014-10-27 07:01 -0700

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