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Hash::Util(3)


NAME

  Hash::Util - A selection of general-utility hash subroutines


SYNOPSIS

    use Hash::Util qw(lock_keys	  unlock_keys
		      lock_value  unlock_value
		      lock_hash	  unlock_hash);

    %hash = (foo => 42, bar => 23);
    lock_keys(%hash);
    lock_keys(%hash, @keyset);
    unlock_keys(%hash);

    lock_value	(%hash, 'foo');
    unlock_value(%hash, 'foo');

    lock_hash  (%hash);
    unlock_hash(%hash);


DESCRIPTION

  "Hash::Util" contains special functions for manipulating hashes that don't
  really warrant a keyword.

  By default "Hash::Util" does not export anything.

  Restricted hashes

  5.8.0 introduces the ability to restrict a hash to a certain set of keys.
  No keys outside of this set can be added.  It also introduces the ability
  to lock an individual key so it cannot be deleted and the value cannot be
  changed.

  This is intended to largely replace the deprecated pseudo-hashes.

  lock_keys
  unlock_keys
	lock_keys(%hash);
	lock_keys(%hash, @keys);

      Restricts the given %hash's set of keys to @keys.	 If @keys is not
      given it restricts it to its current keyset.  No more keys can be
      added.  delete() and exists() will still work, but it does not effect
      the set of allowed keys.

	unlock_keys(%hash;)

      Removes the restriction on the %hash's keyset.

  lock_value
  unlock_value
	lock_key  (%hash, $key);
	unlock_key(%hash, $key);

      Locks and unlocks an individual key of a hash.  The value of a locked
      key cannot be changed.

      %hash must have already been locked for this to have useful effect.

  lock_hash
  unlock_hash
	  lock_hash(%hash);

      lock_hash() locks an entire hash, making all keys and values readonly.
      No value can be changed, no keys can be added or deleted.

	  unlock_hash(%hash);

      unlock_hash() does the opposite of lock_hash().  All keys and values
      are made read/write.  All values can be changed and keys can be added
      and deleted.


AUTHOR

  Michael G Schwern <schwern@pobox.com> on top of code by Nick Ing-Simmons
  and Jeffrey Friedl.


SEE ALSO

  Scalar::Util, List::Util, Hash::Util

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