CONTENTS

• NAME
• SYNOPSIS
• FUNCTIONS
• DESCRIPTION
  • The Inside-out Technique
  • Problems of Inside-out
  • Solutions
  • More Problems
  • The Generic Object
  • How to use Field Hashes
  • Garbage-Collected Hashes
• EXAMPLES
  • Example 1
  • Example 2
• GUTS
  • The PERL_MAGIC_uvar interface for hashes
  • Weakrefs call uvar magic
  • How field hashes work
  • Internal function Hash::Util::FieldHash::_fieldhash
• AUTHOR
• COPYRIGHT AND LICENSE

#NAME

Hash::Util::FieldHash - Support for Inside-Out Classes

#SYNOPSIS

### Create fieldhashes
use Hash::Util qw(fieldhash fieldhashes);

# Create a single field hash
fieldhash my %foo;

# Create three at once...
fieldhashes \ my(%foo, %bar, %baz);
# ...or any number
fieldhashes @hashrefs;

### Create an idhash and register it for garbage collection
use Hash::Util::FieldHash qw(idhash register);
idhash my %name;
my $object = \ do { my $o };
# register the idhash for garbage collection with $object
register($object, \ %name);
# the following entry will be deleted when $object goes out of scope
$name{$object} = 'John Doe';

### Register an ordinary hash for garbage collection
use Hash::Util::FieldHash qw(id register);
my %name;
my $object = \ do { my $o };
# register the hash %name for garbage collection of $object's id
register $object, \ %name;
# the following entry will be deleted when $object goes out of scope
$name{id $object} = 'John Doe';

#FUNCTIONS

Hash::Util::FieldHash offers a number of functions in support of "The Inside-out Technique" of class construction.