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

Ok this is driving me nuts. I Thought I could figure it out myself however I think Its time to ask the monks.
So here it is. I got this piece of code: 

foreach ($self->{'sections'})
{
  ..use $_ here to do stuff..
}

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But I can't seem to access the value in $_ I tried to figure out what type of value it was by doing this: 

print ref($_);

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And I got nothing back. SO I googled around and I found the following snipper: 

   my $val = $_;

   use Carp qw(confess);
   if ( ! defined $val ) {
      return 'null';
   } elsif ( ! ref($val) ) {
      if ( $val =~ /^-?\d+$/ ) {
         return 'int';
      } elsif ( $val =~ /^-?\d+(\.\d+)?$/ ) {
         return 'float';
      } else {
         return 'string';
      }
   } else {
      my $type = ref($val);
      if ( $type eq 'HASH' || $type eq 'ARRAY' ) {
         return 'array';
      } elsif ( $type eq 'CODE' || $type eq 'REF' || $type eq 'GLOB' |
+| $type eq 'LVALUE' ) {
         return $type;
      } else {
         # Object...
         return 'obj';
      }
   }

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This code also returned nothing. When I just print $_ I get a value 300 something (I think this is the amount of dimentions the array has). This snipper will show you how the Variable is defined as is. 

my $sections = (qx!rabin -Svv $filename!);
my @detected_sections = ();
while ($sections =~ m/idx\=(\d*) address=(0x(\d|[a-f])*) offset=(0x(\d
+|[a-f])*) size=(\d*) align=(0x(\d|[a-f])*) perm=((r|w|x|-){4}) name=(
+.*)/gi)
{
   my %section_int = ( index => $1, address => $2, offset => $4, size 
+=> $6, align => $7, rights => $9, name => $11 );
   push (@detected_sections, %section_int);
}
$report->{'sections'} = @detected_sections;

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So am I stupid to guess that the foreach will do foreach array and I would get a hash but I can't use the $_ still in anyway.
So My Question is, What am I doing wrong? And how can I use the $_ in question?


Thanks in advance!
--Robin

Replies are listed 'Best First'.
Re: Variable Unusable?
by GrandFather (Saint) on Dec 29, 2009 at 10:15 UTC

    As a matter of style it is good practice to always use a locally declared (lexical) loop variable in for loops. It makes the scope of the variable clear and avoids issues with knowing what may be mucking with $_ within the scope of the loop.

    True laziness is hard work
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Re: Variable Unusable?
by Anonymous Monk on Dec 29, 2009 at 08:46 UTC
    probable error 
       push (@detected_sections, %section_int);

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    you probably meant \%section_int

    another error here 

    $report->{'sections'} = @detected_sections;

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    an array in scalar context returns the number of elements in the array, you probably meant \@detected_sections, and you probably meant 
    foreach ( @{ $self->{'sections'} })
{
  ..use $_ here to do stuff..
}

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[d/l]
[select]
      Thanks!
      That seemed to do the Trick!

      I do know what the \ does normally. But I don't see why I'll have to use References here? Also the @{} thing is new. I guess I'll spend NewYears reading the Camel book.

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        You have to use references to the arrays and hashes because scalars can only contain scalars and references are scalars.

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