Duration(3)						User Contributed Perl Documentation					       Duration(3)

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), ".
";

       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".

       concise( function( ... ) )
	   Concise takes the string output of one of the above functions and makes it more concise.  For example, "ago(4567)" returns "1 hour and
	   16 minutes ago", but "concise(ago(4567))" returns "1h16m ago".

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

       Current maintainer Avi Finkel, "avi@finkel.org"; Original author Sean M. Burke, "sburke@cpan.org"

perl v5.12.1							    2007-08-19							       Duration(3)