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]

Carter's compass: I know I'm on the right track when by deleting something, I'm adding functionality

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]