dereferencing multiple hash array structure

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

Trying to extract info from an array or hash that is inside multiple hash and array structure in a perl module generated by doxygen. I can extract most everything except what is inside detailed -> doc -> params -> parameters in following DoxyDocs1.pm

Uncomment commented sections to see data trying to extract

Including small sample of code

#!/bin/perl
use Data::Dumper;
use warnings;
require "DoxyDocs1.pm";
print "API Content Analyzer\n";
&GenerateClassInfo($doxydocs->{classes});
sub GenerateClassInfo()
{
    my ($classes) = @_;    
    foreach my $class (@$classes) {
        print "\nClass name is: $class->{name}\n";
        foreach my $pubmeth (@{$class->{public_methods}->{members}}) {
           print "\n" if exists $pubmeth->{name};
           print "\tpublic methods include: $pubmeth->{name}\n";
           my ($key, $pmcontent) = each (@{$pubmeth->{detailed}->{doc}
+});
           print "\t\tdescription: $pmcontent->{content}\n" if exists 
+$pmcontent->{content};
           # foreach my $pmp (@{$pubmeth->{detailed}->{doc}}) {
             # print "\t\t";
             # print Dumper($pmp);
           # }
           print "\t\tkind: $pubmeth->{kind}\n";
           print "\t\ttype: $pubmeth->{type}\n" if exists $pubmeth->{t
+ype};
        }
        foreach my $privmeth (@{$class->{private_methods}->{members}})
+ {
            print "\n" if exists $privmeth->{name};
            print "\tprivate methods include: $privmeth->{name}\n";
            my ($key, $pmcontent) = each (@{$privmeth->{detailed}->{do
+c}});
            print "\t\tdescription: $pmcontent->{content}\n" if exists
+ $pmcontent->{content};
            # foreach my $info (@{$privmeth->{detailed}->{doc}}) {
             # print "\t\t";
             # print Dumper($info);
            # }
            print "\t\tkind: $privmeth->{kind}\n";
            print "\t\ttype: $privmeth->{type}\n" if exists $privmeth-
+>{type};
        }        
    }
}
[download]

DoxyDocs1.pm

$doxydocs=
{
  classes => [
    {
      name => 'Panoply::Composite',
      public_methods => {
        members => [
          {
            kind => 'function',
            name => 'addChild',
            virtualness => 'non_virtual',
            protection => 'public',
            static => 'no',
            brief => {},
            detailed => {
              doc => [
                {
                  type => 'text',
                  content => 'Add a child to the container '
                },
                params => [
                  {
                    parameters => [
                      {
                        name => 'child'
                      }
                    ],
                    doc => [
                      {
                        type => 'text',
                        content => 'is the child element to add'
                      }
                    ]
                  }
                ]
              ]
            },
            type => 'void',
            const => 'no',
            volatile => 'no',
            parameters => [
              {
                declaration_name => 'child',
                type => 'Ptr'
              }
            ]
          },
          {
            kind => 'function',
            name => 'operator<',
            virtualness => 'non_virtual',
            protection => 'public',
            static => 'no',
            brief => {},
            detailed => {
              doc => [
                {
                  type => 'text',
                  content => 'Less than operator'
                },
                {
                  type => 'parbreak'
                },
                params => [
                  {
                    parameters => [
                      {
                        name => 'rval'
                      }
                    ],
                    doc => [
                      {
                        type => 'text',
                        content => 'The '
                      },
                      {
                        type => 'url',
                        link => 'classPanoply_1_1Package',
                        content => 'Package'
                      },
                      {
                        type => 'text',
                        content => ' against which we are comparing th
+is one. '
                      }
                    ]
                  }
                ],
                {
                  return => [
                    {
                      type => 'text',
                      content => 'true if this.packageID < rval.packag
+eID, false otherwise.'
                    }
                  ]
                }
              ]
            },
            type => 'bool',
            const => 'yes',
            volatile => 'no',
            parameters => [
              {
                declaration_name => 'rval',
                type => 'const Composite &'
              }
            ]
          },
        ]
      },
      private_methods => {
        members => [
          {
            kind => 'function',
            name => 'addChild',
            virtualness => 'virtual',
            protection => 'private',
            static => 'no',
            brief => {},
            detailed => {
              doc => [
                {
                  type => 'text',
                  content => 'Add a child to the container '
                },
                params => [
                  {
                    parameters => [
                      {
                        name => 'child'
                      }
                    ],
                    doc => [
                      {
                        type => 'text',
                        content => 'is the child element to add '
                      }
                    ]
                  },
                  {
                    parameters => [
                      {
                        name => 'parent'
                      }
                    ],
                    doc => [
                      {
                        type => 'parbreak'
                      },
                      {
                        type => 'text',
                        content => 'is this own parent, except in weak
+ pointer format to avoid a memory leak'
                      }
                    ]
                  }
                ]
              ]
            },
            type => 'virtual void',
            const => 'no',
            volatile => 'no',
            parameters => [
              {
                declaration_name => 'child',
                type => 'Ptr'
              },
              {
                declaration_name => 'parent',
                type => 'Ptr'
              }
            ]
          },
        ]
      },
    }
  ]
};
1;
[download]

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Replies are listed 'Best First'.
Re: dereferencing multiple hash array structure by GrandFather (Saint) on Jun 23, 2012 at 03:09 UTC
Prior to Perl 5.12 each expects a hash but you are giving it an array. From Perl 5.12 onward the code is syntactically correct, but probably doesn't do what you expect. True laziness is hard work	[reply]
Re: dereferencing multiple hash array structure by Athanasius (Archbishop) on Jun 23, 2012 at 03:40 UTC
Here is an extract from the data structure in DoxyDocs1.pm, re-formatted for greater readability and with one `=>` re-written as quote + comma (see Comma Operator in perlop): `detailed => { doc => [ { type => 'text', content => 'Add a child to the container ' }, "params", [ { parameters => [ { name => 'child' } ], doc => [ { type => 'text', content => 'is the child element to add' } ] } ] ] },` [download] As you can see, `doc` is a hash key with a reference to an anonymous array as its value. This array contains 3 elements: a reference to an anonymous hash; the string `"params"`; and a reference to an anonymous array. As GrandFather says, this is syntactically OK, but it is almost certainly not what was intended — which is why you’re unable to extract the data you want. You will need to re-consider the way this data structure is generated. Update: Using prototypes on subroutines is usually a bad idea, unless you have a strong reason to. Better to remove the trailing parentheses from the definition of `sub GenerateClassInfo`; then call it without the `&` prefix. HTH, Athanasius <°(((>< contra mundum	[reply] [d/l]
Re^2: dereferencing multiple hash array structure by AnomalousMonk (Archbishop) on Jun 23, 2012 at 15:13 UTC
Using prototypes on subroutines is usually a bad idea... Further to Athanasius's point: The function `GenerateClassInfo` is prototyped to take zero arguments, but is defined as operating on a single argument. The only way this function can work as defined is to defeat the prototyping mechanism by calling the function with the `&` sigil. But what's the point of all that? Wasted motion of that sort is one of the reasons prototypes have a bad reputation. For far more, see Far More than Everything You've Ever Wanted to Know about Prototypes in Perl -- by Tom Christiansen. (Update: Furthermore, the `GenerateClassInfo` function is called before it is either defined or declared, i.e., before its prototype is available for checking. This would have generated a warning had the function not been called with the `&` sigil.)	[reply] [d/l] [select]