scalar grep not binding hash slots

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

Can someone tell me why rules and rules2 are not being bound by the use of scalar grep? Any help is appreciated.

CODE

 {
      my @DRIVER = Alzabo::Driver->available;
      my @RULE =   Alzabo::RDBMSRules->available;
      my $sg = (scalar grep { $p{rdbms} eq $_ } Alzabo::RDBMSRules->av
+ailable);
      warn Data::Dumper->Dump([\@DRIVER, \@RULE, $sg], [qw(DRIVER RULE
+ sg)] );
      my %has =
    (
     driver => grep { $p{rdbms} eq $_ } Alzabo::Driver->available,
     rules  => (scalar grep { $p{rdbms} eq $_ } Alzabo::RDBMSRules->av
+ailable)
     ? 'yes' : 'no',
     rules2 => (scalar grep { $p{rdbms} eq $_ } Alzabo::RDBMSRules->av
+ailable)
    );
      use Data::Dumper;
      die Dumper(\%has);
[download]

OUTPUT



        ~/hacks/gerbold/scripts $ perl s.pl
$DRIVER = [
            'Gerbold',
            'MySQL',
            'PostgreSQL'
          ];
$RULE = [
          'MySQL',
          'PostgreSQL'
        ];
$sg = 0;
$VAR1 = {
          'driver' => 'Gerbold'
        };
        ~/hacks/gerbold/scripts $
[download]

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Comment on scalar grep not binding hash slots Select or Download Code

Replies are listed 'Best First'.
Re: scalar grep not binding hash slots by japhy (Canon) on Nov 11, 2003 at 23:56 UTC
You've got TWO problems. You need to limit the arguments to the `grep()`, and you need to use an array reference, not a list, as the value of the 'driver' key in the hash. In fact, by doing the second one, you do the first. `my %hash = ( driver => [ grep $p{rdbms} eq $_, Alzabo::Driver->available ], rules => scalar(grep $p{rdbms} eq $_, Alzabo::RDBMSRules->available +) ? 'yes' : 'no', rules2 => scalar(grep $p{rdbms} eq $_, Alzabo::RDBMSRules->available +), );` [download] _____________________________________________________ Jeff`[japhy]`Pinyan: Perl, regex, and perl hacker, who'd like a job (NYC-area) `s++=END;++y(;-P)}y js++=;shajsj<++y(p-q)}?print:??;`	[reply] [d/l] [select]
Re: scalar grep not binding hash slots by Roger (Parson) on Nov 11, 2003 at 23:26 UTC
Problem is not with your $rules nor $rules2, it's with your `driver=>` line. Change your code to this and your code with work - `my %has = ( # japhy was right, use [ ] to return reference to array driver => [grep { $p{rdbms} eq $_ } Alzabo::Driver->available], rules => (scalar grep { $p{rdbms} eq $_ } Alzabo::RDBMSRules->av +ailable) ? 'yes' : 'no', rules2 => (scalar grep { $p{rdbms} eq $_ } Alzabo::RDBMSRules->av +ailable) );` [download]	[reply] [d/l] [select]
Re: scalar grep not binding hash slots by ysth (Canon) on Nov 11, 2003 at 23:30 UTC
The rules and rules2 lines are part of the list input to the first grep. Try: `(driver => grep { $p{rdbms} eq $_ } Alzabo::Driver->available),`	[reply] [d/l]


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