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Groups > comp.lang.java.programmer > #37458

Re: underscore as keyword in Java 9

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Yeah, somehow it would work if a "_" is
an ordinary variable, for example in:

_, y, _ := coord(p)

Then "_" could be an integer (or what
ever number is used in coord).

Then we would have:

   "_" gets assigned by a value (the x from coord)
   y gets assigne by a value (the y from coord)
   "_" gets assigned, overridden, by a value (the z from coord)

But now there is a problem, what if
we have such a code:

_, _, e = person(z)

And if person returns for example (name:String,
age:integer, employer:String). Then Andreas
Leitgrebs re-enablement is just phantasie,

since in a type safe language, this simple
translation with the same variable "_"
doesn't work:

   "_" gets assigned by a value (the name from person)
   "_" gets assigned, overridden, by a value (the age from coord)
   e gets assigned by a value (the employer from person)

The two "_" are in type conflict. But Garbage
collection and everything in Java needs types.
So there is no re-enablement whatever,

this would be a new feature. A requirement
would be that "_" is really really short lived,
and quickly losses its type and can acquire

another type...

> Arne Vajhøj <arne@vajhoej.dk> wrote:
>> On 9/23/2017 12:46 PM, j4n bur53 wrote:
>>> As long as Java doesn't have multi-returns, there
>>> will be not many use cases. For multi returns, if
>>> they were in the Java language, it could be offered
>>> as in the Go Programming Language:
>>> /* fetching the y coordinate of a 3D point */
>>> _, y, _ := coord(p)
>> I suspect that Java will get that in version 10 or 11.
>> Reason: C# got it in version 7 (and Java and C# tend
>> to steal ideas from each other).
>> Syntax like:
>> (int v1,int v2) = M();
>
> These speculations are entirely orthogonal to the point that "_"
> is taken away from the realm of identifiers, but might in future
> be used syntactically like throw-away identifiers - A use they
> sometimes already have - and this particular use is now being
> forbidden just before likely being re-enabled.
>

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underscore as keyword in Java 9 Andreas Leitgeb <avl@logic.at> - 2017-09-23 11:58 +0000
  Re: underscore as keyword in Java 9 j4n bur53 <janburse@fastmail.fm> - 2017-09-23 18:46 +0200
    Re: underscore as keyword in Java 9 Arne Vajhøj <arne@vajhoej.dk> - 2017-09-23 21:01 -0400
      Re: underscore as keyword in Java 9 Andreas Leitgeb <avl@logic.at> - 2017-09-24 11:25 +0000
        Re: underscore as keyword in Java 9 j4n bur53 <janburse@fastmail.fm> - 2017-09-24 17:30 +0200
        Re: underscore as keyword in Java 9 Arne Vajhøj <arne@vajhoej.dk> - 2017-09-24 18:24 -0400
          Re: underscore as keyword in Java 9 Andreas Leitgeb <avl@logic.at> - 2017-09-24 23:27 +0000
            Re: underscore as keyword in Java 9 Arne Vajhøj <arne@vajhoej.dk> - 2017-09-24 21:10 -0400
              Re: underscore as keyword in Java 9 Andreas Leitgeb <avl@logic.at> - 2017-09-25 13:30 +0000
    Re: underscore as keyword in Java 9 Eric Douglas <e.d.programmer@gmail.com> - 2017-09-25 08:07 -0700
      Re: underscore as keyword in Java 9 lewbloch@gmail.com - 2017-09-25 13:21 -0700
      Re: underscore as keyword in Java 9 Silvio <silvio@internet.com> - 2017-09-25 23:30 +0200
        Re: underscore as keyword in Java 9 Arne Vajhøj <arne@vajhoej.dk> - 2017-09-25 20:24 -0400
          Re: underscore as keyword in Java 9 j4n bur53 <janburse@fastmail.fm> - 2017-09-26 13:37 +0200
          Re: underscore as keyword in Java 9 Silvio <silvio@internet.com> - 2017-09-27 19:05 +0200
            Re: underscore as keyword in Java 9 Eric Douglas <e.d.programmer@gmail.com> - 2017-09-27 10:25 -0700
              Re: underscore as keyword in Java 9 Silvio <silvio@internet.com> - 2017-09-27 23:02 +0200
            Re: underscore as keyword in Java 9 Arne Vajhøj <arne@vajhoej.dk> - 2017-09-27 20:02 -0400
              Re: underscore as keyword in Java 9 Eric Douglas <e.d.programmer@gmail.com> - 2017-09-28 05:11 -0700
                Re: underscore as keyword in Java 9 Arne Vajhøj <arne@vajhoej.dk> - 2017-09-28 20:42 -0400
          Re: underscore as keyword in Java 9 Sebastian <nowhere@nirvana.org> - 2017-09-27 20:26 +0200
            Re: underscore as keyword in Java 9 Silvio <silvio@internet.com> - 2017-09-27 23:10 +0200
        Re: underscore as keyword in Java 9 Andreas Leitgeb <avl@logic.at> - 2017-09-26 08:29 +0000
          Re: underscore as keyword in Java 9 Silvio <silvio@internet.com> - 2017-09-27 19:08 +0200
          Re: underscore as keyword in Java 9 Sebastian <nowhere@nirvana.org> - 2017-09-27 21:46 +0200
  Re: underscore as keyword in Java 9 Eric Douglas <e.d.programmer@gmail.com> - 2017-09-27 06:53 -0700
    Re: underscore as keyword in Java 9 Andreas Leitgeb <avl@logic.at> - 2017-09-27 15:59 +0000
      Re: underscore as keyword in Java 9 Arne Vajhøj <arne@vajhoej.dk> - 2017-09-27 19:18 -0400
        Re: underscore as keyword in Java 9 Daniele Futtorovic <da.futt.news@laposte.net> - 2017-09-28 11:41 +0200

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