README for Time::Duration

NAME
    Time::Duration -- rounded or exact English expression of durations

SYNOPSIS
    Example use in a program that ends by noting its runtime:

      my $start_time = time();
      use Time::Duration;
      
      # then things that take all that time, and then ends:
      print "Runtime ", duration(time() - $start_time), ".\n";

    Example use in a program that reports age of a file:

      use Time::Duration;
      my $file = 'that_file';
      my $age = $^T - (stat($file))[9];  # 9 = modtime
      print "$file was modified ", ago($age);

DESCRIPTION
    This module provides functions for expressing durations in rounded
    or exact terms.

    In the first example in the Synopsis, using
    duration($interval_seconds):

    If the `time() - $start_time' is 3 seconds, this prints "Runtime:
    3 seconds.". If it's 0 seconds, it's "Runtime: 0 seconds.". If
    it's 1 second, it's "Runtime: 1 second.". If it's 125 seconds, you
    get "Runtime: 2 minutes and 5 seconds.". If it's 3820 seconds
    (which is exactly 1h, 3m, 40s), you get it rounded to fit within
    two expressed units: "Runtime: 1 hour and 4 minutes.". Using
    duration_exact instead would return "Runtime: 1 hour, 3 minutes,
    and 40 seconds".

    In the second example in the Synopsis, using
    ago($interval_seconds):

    If the $age is 3 seconds, this prints "*file* was modified 3
    seconds ago".  If it's 0 seconds, it's "*file* was modified just
    now", as a special case.  If it's 1 second, it's "from 1 second
    ago". If it's 125 seconds, you get "*file* was modified 2 minutes
    and 5 seconds ago". If it's 3820 seconds (which is exactly 1h, 3m,
    40s), you get it rounded to fit within two expressed units:
    "*file* was modified 1 hour and 4 minutes ago". Using ago_exact
    instead would return "*file* was modified 1 hour, 3 minutes, and
    40 seconds ago". And if the file's modtime is, surprisingly, three
    seconds into the future, $age is -3, and you'll get the equally
    and appropriately surprising "*file* was modified 3 seconds from
    now."

FUNCTIONS
    This module provides all the following functions, which are all
    exported by default when you call `use Time::Duration;'.

    duration($seconds)
    duration($seconds, $precision)
        Returns English text expressing the approximate time duration
        of abs($seconds), with at most `$precision || 2' expressed
        units. (That is, duration($seconds) is the same as
        duration($seconds,2).)

        For example, duration(120) or duration(-120) is "2
        minutes". And duration(0) is "0 seconds".

        The precision figure means that no more than that many units
        will be used in expressing the time duration. For example,
        31,629,659 seconds is a duration of *exactly* 1 year, 1 day, 2
        hours, and 59 seconds (assuming 1 year = exactly 365 days, as
        we do assume in this module). However, if you wanted an
        approximation of this to at most two expressed (i.e., nonzero)
        units, it would round it and truncate it to "1 year and 1
        day".  Max of 3 expressed units would get you "1 year, 1 day,
        and 2 hours". Max of 4 expressed units would get you "1 year,
        1 day, 2 hours, and 59 seconds", which happens to be exactly
        true. Max of 5 (or more) expressed units would get you the
        same, since there are only four nonzero units possible in for
        that duration.

    duration_exact($seconds)
        Same as duration($seconds), except that the returned value is
        an exact (unrounded) expression of $seconds. For example,
        duration_exact(31629659) returns "1 year, 1 day, 2 hours, and
        59 seconds later", which is *exactly* true.

    ago($seconds)
    ago($seconds, $precision)
        For a positive value of seconds, this prints the same as
        `duration($seconds, [$precision]) . ' ago''. For example,
        ago(120) is "2 minutes ago". For a negative value of seconds,
        this prints the same as `duration($seconds, [$precision]) . '
        from now''. For example, ago(-120) is "2 minutes from now". As
        a special case, ago(0) returns "right now".

    ago_exact($seconds)
        Same as ago($seconds), except that the returned value is an
        exact (unrounded) expression of $seconds.

    from_now($seconds)
    from_now($seconds, $precision)
    from_now_exact($seconds)
        The same as ago(-$seconds), ago(-$seconds, $precision),
        ago_exact(- $seconds). For example, from_now(120) is "2
        minutes from now".

    later($seconds)
    later($seconds, $precision)
        For a positive value of seconds, this prints the same as
        `duration($seconds, [$precision]) . ' later''. For example,
        ago(120) is "2 minutes later". For a negative value of
        seconds, this prints the same as `duration($seconds,
        [$precision]) . ' earlier''. For example, later(- 120) is "2
        minutes earlier". As a special case, later(0) returns "right
        then".

    later_exact($seconds)
        Same as later($seconds), except that the returned value is an
        exact (unrounded) expression of $seconds.

    earlier($seconds)
    earlier($seconds, $precision)
    earlier_exact($seconds)
        The same as later(-$seconds), later(-$seconds, $precision),
        later_exact(-$seconds). For example, earlier(120) is "2
        minutes earlier".

I18N/L10N NOTES
    Little of the internals of this module are English-specific. See
    source and/or contact me if you're interested in making a
    localized version for some other language than English.

BACKSTORY
    I wrote the basic `ago()' function for use in Infobot
    (`http://www.infobot.org'), because I was tired of this sort of
    response from the Purl Infobot:

      me> Purl, seen Woozle?
      <Purl> Woozle was last seen on #perl 20 days, 7 hours, 32 minutes
      and 40 seconds ago, saying: Wuzzle!

    I figured if it was 20 days ago, I don't care about the
    seconds. So once I had written `ago()', I abstracted the code a
    bit and got all the other functions.

CAVEAT
    This module calls a durational "year" an interval of exactly 365
    days of exactly 24 hours each, with no provision for leap years or
    monkey business with 23/25 hour days (much less leap
    seconds!). But since the main work of this module is
    approximation, that shouldn't be a great problem for most
    purposes.

SEE ALSO
    Date::Interval, which is similarly named, but does something
    rather different.

    *Star Trek: The Next Generation* (1987-1994), where the character
    Data would express time durations like "1 year, 20 days, 22 hours,
    59 minutes, and 35 seconds" instead of rounding to "1 year and 21
    days". This is because no-one ever told him to use Time::Duration.

COPYRIGHT AND DISCLAIMER
    Copyright 2006, Sean M. Burke `sburke@cpan.org', all rights
    reserved. This program is free software; you can redistribute it
    and/or modify it under the same terms as Perl itself.

    This program is distributed in the hope that it will be useful,
    but without any warranty; without even the implied warranty of
    merchantability or fitness for a particular purpose.

AUTHOR
    Original Author: Sean M. Burke, `sburke@cpan.org'
		Maintainer: Avi Finkel, `avi@finkel.org'



PREREQUISITES

This suite requires Perl 5.

Time::Duration doesn't use any nonstandard modules.


INSTALLATION

You install Time::Duration, as you would install any perl module
library, by running these commands:

   perl Makefile.PL
   make
   make test
   make install

If you want to install a private copy of Time::Duration in your home
directory, then you should try to produce the initial Makefile with
something like this command:

  perl Makefile.PL LIB=~/perl

See perldoc perlmodinstall for more information.


DOCUMENTATION

POD-format documentation is included in Duration.pm.  POD is readable
with the 'perldoc' utility.  See ChangeLog for recent changes.


MACPERL INSTALLATION NOTES

Don't bother with the makefiles.  Just make a Time directory in your
MacPerl site_lib or lib directory, and move Duration.pm into there.


SUPPORT

Questions, bug reports, useful code bits, and suggestions for
Time::Duration should just be sent to me at avi@finkel.org


AVAILABILITY

The latest version of Time::Duration is available from the
Comprehensive Perl Archive Network (CPAN).  Visit
<http://www.perl.com/CPAN/> to find a CPAN site near you.
