NAME
    Algorithm::Permute - Handy and fast permutation with object
    oriented interface

SYNOPSIS
      use Algorithm::Permute;

      $p = new Algorithm::Permute(['a'..'d']);
      while (@res = $p->next) {
        print join(", ", @res), "\n";
      }

DESCRIPTION
    This handy module makes performing permutation in Perl easy and
    fast, although perhaps its algorithm is not the fastest on the
    earth. Currently it only supports permutation n of n objects.

    No exported functions. This version is not backward compatible
    with the previous one, version 0.01. The old interface is no
    longer supported.

METHODS
    new [@list]
        Returns a permutor object for the given items.

    next
        Returns a list of the items in the next permutation. The
        order of the resulting permutation is the same as of the
        previous version of `Algorithm::Permute'.

    peek
        Returns the list of items which will be returned by next(),
        but doesn't advance the sequence. Could be useful if you
        wished to skip over just a few unwanted permutations.

    reset
        Resets the iterator to the start. May be used at any time,
        whether the entire set has been produced or not. Has no
        useful return value.

COMPARISON
    I've collected some Perl routines and modules which implement
    permutation, and do some simple benchmark. The result, which is
    of course predictable, and obvious, is the following.

    Permutation of eight scalars:

      Abigail's: 14 wallclock secs (13.21 usr +  0.49 sys = 13.70 CPU)
      Algorithm::Permute:  3 wallclock secs ( 2.96 usr +  0.02 sys =  2.98 CPU)
      List::Permutor:  9 wallclock secs ( 8.98 usr +  0.02 sys =  9.00 CPU)
         MJD's: 56 wallclock secs (55.54 usr +  0.18 sys = 55.72 CPU)
      perlfaq4: 65 wallclock secs (64.71 usr +  0.22 sys = 64.93 CPU)

    Permutation of nine scalars (the Abigail's routine is commented
    out, because it stores all of the result in memory, swallows all
    of my machine's memory):

      Algorithm::Permute: 14 wallclock secs (14.13 usr +  0.07 sys = 14.20 CPU)
      List::Permutor: 67 wallclock secs (65.78 usr +  0.47 sys = 66.25 CPU)
         MJD's: 530 wallclock secs (516.57 usr +  2.10 sys = 518.67 CPU)
      perlfaq4: 498 wallclock secs (490.49 usr +  1.65 sys = 492.14 CPU)

    The benchmark script is included in the bench directory. I
    understand that speed is not everything. So here is the list of
    URLs of the alternatives, in case you hate this module.

    * 
    Mark Jason Dominus' technique is discussed in chapter 4 Perl Cookbook, so you 
    can get it from O'Reilly: 
    ftp://ftp.oreilly.com/published/oreilly/perl/cookbook
    *
    Abigail's: http://www.foad.org/~abigail/Perl
    *
    List::Permutor: http://www.cpan.org/modules/by-module/List
    *
    The classic way, usually used by Lisp hackers: perldoc perlfaq4
HISTORY
    *   September 2, 2000 - version 0.02. Major interface changes, now
        using object oriented interface similar to
        `List::Permutor''s. More efficient memory usage. Internal
        tweaking gives speed improvement - the list elements are no
        longer swapped, but only the indexes.

    *   October 3, 1999 - Alpha release, version 0.01

AUTHOR
    Edwin Pratomo, *ed.pratomo@computer.org*. The object oriented
    interface is taken from Tom Phoenix's `List::Permutor'.

ACKNOWLEDGEMENT
    Yustina Sri Suharini - my fiance, for providing the permutation
    problem to me.

SEE ALSO
    * Data Structures, Algorithms, and Program Style Using C - 
    Korsh and Garrett
    * Algorithms from P to NP, Vol. I - Moret and Shapiro