Stanislav has asked for the wisdom of the Perl Monks concerning the following question:

Hi all I installed parrot in this way: 
$ svn co https://svn.perl.org/parrot/trunk parrot
$ cd parrot
$ perl Configure.pl; make
$ cd languages/perl6/; make perl6

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Then I took an example of class from wiki http://en.wikipedia.org/wiki/Perl_6. Here is code: 
#!/home/stas/perl/parrot/languages/perl6/perl6
class Point is rw {
  has $.x;
  has $.y;
}

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When I try to execute this script I get: 
Attempt to inherit from non-existent parent class
current instr.: 'die' pc 12249 (src/gen_builtins.pir:7489)
called from Sub 'trait_auxiliary:is' pc 15862 (src/gen_builtins.pir:99
+27)
called from Sub '_block13' pc 122 (EVAL_12:47)
called from Sub 'parrot;PCT;HLLCompiler;evalpmc' pc 804 (src/PCT/HLLCo
+mpiler.pir:468)
called from Sub 'parrot;PCT;HLLCompiler;compile' pc 434 (src/PCT/HLLCo
+mpiler.pir:303)
called from Sub 'parrot;PCT;HLLCompiler;eval' pc 836 (src/PCT/HLLCompi
+ler.pir:493)
called from Sub 'parrot;PCT;HLLCompiler;evalfiles' pc 1201 (src/PCT/HL
+LCompiler.pir:667)
called from Sub 'parrot;PCT;HLLCompiler;command_line' pc 1380 (src/PCT
+/HLLCompiler.pir:756)
called from Sub 'parrot;Perl6;Compiler;main' pc 16140 (perl6.pir:168)

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Where is problem? May be it's not implemented yet... Thanks

Replies are listed 'Best First'.
Re: Perl 6 class
by moritz (Cardinal) on Nov 18, 2008 at 15:34 UTC
    It seems that the is rw trait on a class is interpreted as is $classname (which means inheritance), and actually I'm not sure if the is rw trait on a class is even in the specs (Update: it's an example in the spec, but I'm not sure what it means).

    Try it without the first is rw instead. The ones on the attributes should be fine.

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      Thanks moritz for the reply. I've already tried without 'is rw' and it works, and also I saw a spec. But, the question is why I see the same example in spec: 
      Class traits are set using is:

    class MyStruct is rw {...}

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      and also see the same construction in wiki and it isn't work. You wrote:
      (Update: it's an example in the spec, but I'm not sure what it means)
      I think it means (from the spec):
      If you declare the class as rw, then all the class's attributes default to rw, much like a C struct.
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[d/l]
        Stanislav,
        I am not sure moritz's answer explained things completely. If you understood great. If not (for those following along at home), here is more of the story. Unlike perl 5, perl 6 will not be specification by implementation. It has an independent specification and any implementation that passes the perl 6 test suite will be consider perl 6. While the perl 6 specification is still changing (very slowly - more fine tuning at this point), there are a number of implementations that are in various stages of completion. The Rakudo (perl 6 on parrot) implementation is not yet meeting the spec in this regard. That's the simple answer.

        See Getting Involved with Perl 6 - an Update for more information.

        Cheers - L~R

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        I've opened a ticket (perl 60636) for that, but I don't think it's high priority at the moment so it might take some time to get fixed (though patches are always welcome, and Patrick, Jonathan, Masak and I always try to review and apply them quickly).
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