NAME

Devel::Size::Report - generate a size report for all elements in a structure

SYNOPSIS

        use Devel::Size::Report qw/report_size/;

        my $a = [ 8, 9, 7,
                  [ \"12",
                    2, 3,
                    { a => 'b',
                      size => 12.2,
                      h => ['a']
                    },
                    sub { 42; },
                  'rrr'
                  ] ];
        print report_size($a, { indend => "   " } );

This will print something like this:

        Size report v0.04 for 'ARRAY(0x815a430)':
          Array 743 bytes (overhead: 84 bytes, 11.31%)
             Scalar 16 bytes
             Scalar 16 bytes
             Scalar 16 bytes
             Array 611 bytes (overhead: 96 bytes, 15.71%)
                Scalar reference 27 bytes
                Scalar 28 bytes
                Scalar 28 bytes
                Hash 308 bytes (overhead: 180 bytes, 58.44%)
                   'h' => Array 82 bytes (overhead: 56 bytes, 68.29%)
                      Scalar 26 bytes
                   'a' => Scalar 26 bytes
                   'size' => Scalar 20 bytes
                Code 92 bytes
                Scalar 32 bytes
        Total: 743 bytes

DESCRIPTION

Devel::Size can only report the size of a single element or the total size of a structure (array, hash etc). This module enhances Devel::Size by giving you the ability to generate a full size report for each element in a structure.

You have full control over how the generated text report looks like, and where you want to output it. In addition, the method track_size allows you to get at the raw data that is used to generate the report for even more flexibility.

METHODS

report_size

        my $record = report_size( $reference, $options ) . "\n";
        print $record;

Walks the given reference recursively and returns text tree describing the size of each element. $options is a hash, containing the following optional keys:

        names     ref to HASH mapping the types to names
                  This should map S_Scalar to something like "Scalar" etc
        indend    string to indend different levels with, default is '  '
        left      indend all text with this at the left side, default is ''
        inner     indend inner text with this at the left side, default is '  '
        total     if true, a total size will be printed as last line
        bytes     name of the size unit, defaults to 'bytes'
        head      header string, default 'Size report for'
                  Set to '' to supress header completely        
        overhead  Format string for the overhead, first size in bytes, then
                  the bytes string (see above) and then the percentage.
                  The default is:
                  " (overhead: %i%s, %0.2f%%)"
        addr      if true, for each element the memory address will be output
        class     if true, show the class each element was blessed in

entries_per_element

        my $entries = entries_per_element();

Returns the number of entries per element that track_size() will generate.

track_size

        @elements = track_size( $reference, $level);

Walk the given scalar or reference recursively and returns an array, containing entries_per_element entries for each element in the structure pointed to by $reference. $reference can also be a plain scalar.

The entries currently are:

        level     the indend level
        type      the type of the element, S_SCALAR, S_HASH, S_ARRAY etc
                  if (type & S_KEY) != 0, the element is a member of a hash
        size      size in bytes of the element
        overhead  if the element is an ARRAY or HASH, contains the overhead
                  in bytes (size - sum(size of all elements)).
        name      if type & S_KEY != 0, this contains the name of the hash key
        addr      memory address of the element
        class     classname that the element was blessed into, or ''

track_size calls itself recursively for ARRAY and HASH references.

type_name

        $type_number = type($type_name);

Maps a type name (like 'SCALAR') to a type number (lilke S_SCALAR).

WRAP YOUR OWN

If you want to create your own report with different formattings, please use track_size and create a report out of the data you get. Look at the source code for report_size how to do this - it is easy!

CAVEATS

• The limitations of Devel::Size also apply to this module. This means that CODE refs and other "obscure" things might show wrong sizes, or unknown overhead. In addition, some sizes might be reported wrong.

• A string representation of the passed argument will be inserted when generating a report with a header.

  If the passed argument is an object with overloaded magic, then the routine for stringification will be triggered. If this routine does actually modify the object (for instance, Math::String objects cache their string form upon first call to stringification, thus modifying themselves), the reported size will be different from a first report without a header.

BUGS

Apart from the problems with Devel::Size, none known so far.

AUTHOR

(c) 2004 by Tels http://bloodgate.com

cpanm Devel::Size::Report

perl -MCPAN -e shell
install Devel::Size::Report