NAME
    DateTime::Format::Human::Duration - Get a locale specific string
    describing the span of a given duration

SYNOPSIS
        use DateTime;
        use DateTime::Format::Human::Duration

        my $span = DateTime::Format::Human::Duration->new();
        my $dur = $dta - $dtb;
        print $span->format_duration($dur); # 1 year, 2 months, 3 minutes, and 1 second
  
        print $span->format_duration_between($dta, $dtb); # 1 year, 2 months, 3 minutes, and 1 second

DESCRIPTION
    Get a localized string representing the duration.

    For example:

        1 second
        2 minutes and 3 seconds
        3 weeks, 1 day, and 5 seconds
        4 years, 1 month, 2 days, 6 minutes, 1 second, and 345000028 nanoseconds

INTERFACE
  new()
    Create span object, no args

  format_duration()
    First argument is a DateTime::Duration object

    After that you can optionally pass some standard args as a hash as
    described below

  format_duration_between()
    First two args are DateTime objects

    After that you can optionally pass some standard args as a hash as
    described below

  standard args
    1. 'locale'
        locale of the $dt object will be used if you do not specify this

        Valid values are a string of the locale (E.g 'fr'), a DateTime
        object, or a DateTime object's 'locale' key.

    2. Since we're working with 2 DateTime objects of known points we can
    have past and future tenses.
        * past
            String to use if duration is past tense. Can have a sprintf '%s'
            or else is prepended with a trailing space.

        * future
            String to use if duration is future tense. Can have a sprintf
            '%s' or else is prepended with a trailing space.

        * no_time
            Override the 'no_time' in the locale hash.

        If duration is baseless (IE ambiguous) then 'past' and 'future' is
        used based on if $dur->in_units has negatives or not.

        Also by nature it's not split into type groups:

        An example is

          DateTime::Duration->new('seconds'=> 62)
  
        Will result in '62 seconds' not '1 minute and 2 seconds'

        For more sane results always be specific by using 2 datetime object
        to get a duration object

            print $dt->format_duration_between(
                $dta,
                $dtb, 
                'past'   => 'Your account expired %s ago.', 
                'future' => 'Your account expires in %s.', 
                'no_time'=> 'Your account just expired.',
            );

        This facilitates, for example, this Locale::Maketext vernacular
        which becomes:

           'Your account [duration,_1,_2,expired %s ago,expires in,just expired].' => '[Votre compte [duration,_1,_2,a expiré il ya,expire dans,vient d'expirer].'

    3. Time Resolution and Units
        * units
            Specify units to format duration with. Arguments will be passed
            to DateTime::Format's in_unit() method.

            Example:

                my $fmt = DateTime::Format::Human::Duration->new();
                my $d = DateTime::Duration->new(...);
  
                my $s = $fmt->format_duration($d, 'units' => [qw/years months days/] );
                # $s == '1 year, 7 months, and 16 days'

            Possible values include: years months weeks days hours minutes
            seconds nanoseconds

        * precision
            By default, the duration will be formatted using nanosecond
            resolution. Resolution can be reduced by passing 'years',
            'months', 'weeks', 'days', 'hours', 'minutes', or 'seconds' to
            the 'precision' argument.

            Example:

                my $fmt = DateTime::Format::Human::Duration->new();
                my $d = DateTime::Duration->new(...);
  
                print $fmt->format_duration($d);
                # '1 year, 7 months, 2 weeks, 2 days, 13 hours, 43 minutes, and 15 seconds'
  
                print $fmt->format_duration($d, 'precision' => 'days');
                # '1 year, 7 months, 2 weeks, and 2 days'

        * significant_units
            By default, the duration will be formatted using all specified
            units. To restrict the number of units output, set this to a
            value of one or more.

            Example:

                my $fmt = DateTime::Format::Human::Duration->new();
                my $d = DateTime::Duration->new(...);
  
                print $fmt->format_duration($d, 'significant_units' => 1);
                # '3 days'
                print $fmt->format_duration($d, 'significant_units' => 2);
                # '3 days and 10 hours'
                print $fmt->format_duration($d, 'significant_units' => 3);
                # '3 days, 10 hours, and 27 minutes'

LOCALIZATION
    Localization is provided by the included
    DateTime::Format::Human::Duration::Locale modules.

    Included are DateTime::Format::Human::Duration::Locale::es,
    DateTime::Format::Human::Duration::Locale::fr,
    DateTime::Format::Human::Duration::Locale::pt,
    DateTime::Format::Human::Duration::Locale::de,
    DateTime::Format::Human::Duration::Locale::it

    More will be included as time permits/folks volunteer/CLDR becomes an
    option

    They are setup this way:

    DateTime::Format::Human::Duration::Locale::XYZ where 'XYZ' is the ISO
    code of DateTime::Locale

    It can have one of 2 functions:

    get_human_span_hashref()
        Takes no arguments, should return a hashref of this structure:

            sub get_human_span_hashref {
                return {
                    'no_oxford_comma' => 1,
                    'no_time' => 'pas le temps',
                    'and'     => 'et',    
                    'year'  => 'an',
                    'years' => 'ans',
                    'month'  => 'mois',
                    'months' => 'mois',
                    'week'  => 'semaine',
                    'weeks' => 'semaines',
                    'day'  => 'jour',
                    'days' => 'jours',
                    'hour'  => 'heure',
                    'hours' => 'heures',
                    'minute'  => 'minute',
                    'minutes' => 'minutes',
                    'second'  => 'seconde',
                    'seconds' => 'seconds',
                    'nanosecond'  => 'nanoseconde',
                    'nanoseconds' => 'nanosecondes',      
                };
            }

    get_human_span_from_units()
        Try to use get_human_span_hashref() if the locale allows for it
        since it's much easier. If you cannot, however, then this will give
        you the maximum level of configurability.

        This function receives a hashref of duration values, and a hashref
        of the standard args. It should return the localized string.

            sub get_human_span_from_units {
                my ($duration_values_hr, $args_hr) = @_;
                ...;
                return $string; # 1 year, 2days, 4 hours, and 17 minutes
            }

        Please see the example in
        `t/lib/DateTime/Format/Human/Duration/Locale/nb.pm'.

LOCALIZATION of DateTime::Format modules
    DateTime does an excellent job at implementing localization. Often
    DateTime::Format based class's either don't support localization or they
    implement it haphazardly and inconsistently.

    With this module I hope to model a localization scheme that is inline
    with DateTime and is consistent and reuseable between <DateTime::Format>
    based classes.

    The idea is to determine the locale to use based on a DateTime object.

    XYZ::Locale should handle looking up (and caching if appropriate) the
    locale and loading the necessary locale module XYZ::Locale::fr

    The specific locale module holds the data and possibly logic necessary
    to do what XYZ does in the vernacular of the given locale.

  TODO
    Eventually the generic logic will be re-broken out into its own module
    for re-use by your class and I'll have more detailed POD about how to do
    it.

    In the meantime if you're interested please contact me and I'd be happy
    to help and/or expediate this TODO.

    Also, Dave Rolksy has mentioned to me that this sort of locale data
    might be appropriate for DateTime::Locale directly from CLDR. If that
    happens this module will be changed to use that if possible.

FAQ
  Why would I want to use this?
    So you can localize your application's output of time periods without
    having to do a lot of logic each time you wanted to say it.

    Locale::Maketext::Utils has/will have a duration() bracket notation
    method which prompted this module's existence

    duration() was prompted by its datetime() brother, all of which uses the
    most excellent DateTime project!

  Why did my duration say '62 seconds' instead of '1 minute and 2 seconds'
    Because you used an ambiguous duration (one without a base) so there is
    no way to apply date math and accurately represent the number of each
    given item in that duration since it may or may not span leap-[second,
    days, years, etc..]

    In other words do this (so that your duration can be specifically
    calculated):

        $dtb = $dta->clone->add('seconds'=> 62);
        my $duration = $dta - $dtb; # has a base, its not ambiguous
        print $span->format_duration($duration); # 1 minutes and 2 seconds

    not this:

        my $duration = DateTime::Duration->new('seconds'=> 62); # no base, it is ambiguous
        print $span->format_duration($duration); # 62 seconds

    Note format_duration_between(), does not suffer from this since we're
    using a specific DateTime object already.

        print $span->format_duration_between( $dt, $dt->clone()->add('seconds'=> 62) ); # 1 minute and 2 seconds

  Why do you put a comma before the 'and' in a group of more than 2 items?
    We want to use the so-called Oxford comma to avoid ambiguity.

  My DateTime::Format::Human::Duration::Locale::XX still outputs in English!
    That is because it defined neither the get_human_span_hashref() or the
    get_human_span_from_units() functions

    It must define one of them or defaults are used.

  Why didn't you just use 'DateTime::Format::Duration'
    Essencially DateTime::Format::Duration is an object representing a
    single strftime() type string to apply to any given duration. This is
    not flexible enough for the intent of this module.

    DateTime::Format::Duration is not a bad module its just for a different
    purpose than DateTime::Format::Human::Duration

    * It was not localizable
        You either got '2 days' or '1 days' which a) forces it to be in
        English and b) doesn't even make sense in English.

        You could get around that by adding logic each time you wanted to
        call it but that is just messy.

    * Had to keep an item even if it was zero
        If 'days' was in there you got '0 days', we only want items with a
        value to show.

        That'd also require a lot of logic each time you wanted to call
        which is again messy.

    * This module has no need for reparsing output back into an object
        Since the datetime info for 2 points in time are generally in a form
        easily rendered into a DateTime object it'd be silly to even attempt
        to store and parse the output of this module back into an object.

        Plus since it all depends on the locale it is in it'd be difficult.

    The purpose of DateTime::Format::Human::Duration was to generate a
    localized human language description of a duration without the caller
    needing to supply any logic.

DIAGNOSTICS
    Throws no warnings or errors of its own

CONFIGURATION AND ENVIRONMENT
    DateTime::Format::Human::Duration requires no configuration files or
    environment variables.

DEPENDENCIES
    None.

INCOMPATIBILITIES
    None reported.

BUGS AND LIMITATIONS
    No bugs have been reported.

    Please report any bugs or feature requests to
    `[email protected]', or through the web interface at
    http://rt.cpan.org.

AUTHOR
    Daniel Muey `<http://drmuey.com/cpan_contact.pl>'

LICENCE AND COPYRIGHT
    Copyright (c) 2008, Daniel Muey `<http://drmuey.com/cpan_contact.pl>'.
    All rights reserved.

    This module is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself. See perlartistic.

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