Provided by: perl-doc_5.28.1-6_all bug

NAME

       Time::Piece - Object Oriented time objects

SYNOPSIS

           use Time::Piece;

           my $t = localtime;
           print "Time is $t\n";
           print "Year is ", $t->year, "\n";

DESCRIPTION

       This module replaces the standard "localtime" and "gmtime" functions with implementations
       that return objects. It does so in a backwards compatible manner, so that using
       localtime/gmtime in the way documented in perlfunc will still return what you expect.

       The module actually implements most of an interface described by Larry Wall on the
       perl5-porters mailing list here:
       <http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2000-01/msg00241.html>

USAGE

       After importing this module, when you use localtime or gmtime in a scalar context, rather
       than getting an ordinary scalar string representing the date and time, you get a
       Time::Piece object, whose stringification happens to produce the same effect as the
       localtime and gmtime functions. There is also a new() constructor provided, which is the
       same as localtime(), except when passed a Time::Piece object, in which case it's a copy
       constructor. The following methods are available on the object:

           $t->sec                 # also available as $t->second
           $t->min                 # also available as $t->minute
           $t->hour                # 24 hour
           $t->mday                # also available as $t->day_of_month
           $t->mon                 # 1 = January
           $t->_mon                # 0 = January
           $t->monname             # Feb
           $t->month               # same as $t->monname
           $t->fullmonth           # February
           $t->year                # based at 0 (year 0 AD is, of course 1 BC)
           $t->_year               # year minus 1900
           $t->yy                  # 2 digit year
           $t->wday                # 1 = Sunday
           $t->_wday               # 0 = Sunday
           $t->day_of_week         # 0 = Sunday
           $t->wdayname            # Tue
           $t->day                 # same as wdayname
           $t->fullday             # Tuesday
           $t->yday                # also available as $t->day_of_year, 0 = Jan 01
           $t->isdst               # also available as $t->daylight_savings

           $t->hms                 # 12:34:56
           $t->hms(".")            # 12.34.56
           $t->time                # same as $t->hms

           $t->ymd                 # 2000-02-29
           $t->date                # same as $t->ymd
           $t->mdy                 # 02-29-2000
           $t->mdy("/")            # 02/29/2000
           $t->dmy                 # 29-02-2000
           $t->dmy(".")            # 29.02.2000
           $t->datetime            # 2000-02-29T12:34:56 (ISO 8601)
           $t->cdate               # Tue Feb 29 12:34:56 2000
           "$t"                    # same as $t->cdate

           $t->epoch               # seconds since the epoch
           $t->tzoffset            # timezone offset in a Time::Seconds object

           $t->julian_day          # number of days since Julian period began
           $t->mjd                 # modified Julian date (JD-2400000.5 days)

           $t->week                # week number (ISO 8601)

           $t->is_leap_year        # true if it's a leap year
           $t->month_last_day      # 28-31

           $t->time_separator($s)  # set the default separator (default ":")
           $t->date_separator($s)  # set the default separator (default "-")
           $t->day_list(@days)     # set the default weekdays
           $t->mon_list(@days)     # set the default months

           $t->strftime(FORMAT)    # same as POSIX::strftime (without the overhead
                                   # of the full POSIX extension)
           $t->strftime()          # "Tue, 29 Feb 2000 12:34:56 GMT"

           Time::Piece->strptime(STRING, FORMAT)
                                   # see strptime man page. Creates a new
                                   # Time::Piece object

       Note that "localtime" and "gmtime" are not listed above.  If called as methods on a
       Time::Piece object, they act as constructors, returning a new Time::Piece object for the
       current time.  In other words: they're not useful as methods.

   Local Locales
       Both wdayname (day) and monname (month) allow passing in a list to use to index the name
       of the days against. This can be useful if you need to implement some form of localisation
       without actually installing or using locales. Note that this is a global override and will
       affect all Time::Piece instances.

         my @days = qw( Dimanche Lundi Merdi Mercredi Jeudi Vendredi Samedi );

         my $french_day = localtime->day(@days);

       These settings can be overridden globally too:

         Time::Piece::day_list(@days);

       Or for months:

         Time::Piece::mon_list(@months);

       And locally for months:

         print localtime->month(@months);

       Or to populate with your current system locale call:
           Time::Piece->use_locale();

   Date Calculations
       It's possible to use simple addition and subtraction of objects:

           use Time::Seconds;

           my $seconds = $t1 - $t2;
           $t1 += ONE_DAY; # add 1 day (constant from Time::Seconds)

       The following are valid ($t1 and $t2 are Time::Piece objects):

           $t1 - $t2; # returns Time::Seconds object
           $t1 - 42; # returns Time::Piece object
           $t1 + 533; # returns Time::Piece object

       However adding a Time::Piece object to another Time::Piece object will cause a runtime
       error.

       Note that the first of the above returns a Time::Seconds object, so while examining the
       object will print the number of seconds (because of the overloading), you can also get the
       number of minutes, hours, days, weeks and years in that delta, using the Time::Seconds
       API.

       In addition to adding seconds, there are two APIs for adding months and years:

           $t = $t->add_months(6);
           $t = $t->add_years(5);

       The months and years can be negative for subtractions. Note that there is some "strange"
       behaviour when adding and subtracting months at the ends of months. Generally when the
       resulting month is shorter than the starting month then the number of overlap days is
       added. For example subtracting a month from 2008-03-31 will not result in 2008-02-31 as
       this is an impossible date. Instead you will get 2008-03-02. This appears to be consistent
       with other date manipulation tools.

   Truncation
       Calling the "truncate" method returns a copy of the object but with the time truncated to
       the start of the supplied unit.

           $t = $t->truncate(to => 'day');

       This example will set the time to midnight on the same date which $t had previously.
       Allowed values for the "to" parameter are: "year", "quarter", "month", "day", "hour",
       "minute" and "second".

   Date Comparisons
       Date comparisons are also possible, using the full suite of "<", ">", "<=", ">=", "<=>",
       "==" and "!=".

   Date Parsing
       Time::Piece has a built-in strptime() function (from FreeBSD), allowing you incredibly
       flexible date parsing routines. For example:

         my $t = Time::Piece->strptime("Sunday 3rd Nov, 1943",
                                       "%A %drd %b, %Y");

         print $t->strftime("%a, %d %b %Y");

       Outputs:

         Wed, 03 Nov 1943

       (see, it's even smart enough to fix my obvious date bug)

       For more information see "man strptime", which should be on all unix systems.

       Alternatively look here: <http://www.unix.com/man-page/FreeBSD/3/strftime/>

       CAVEAT %A, %a, %B, %b, and friends

       Time::Piece::strptime by default can only parse American English date names.  Meanwhile,
       Time::Piece->strftime() will return date names that use the current configured system
       locale. This means dates returned by strftime might not be able to be parsed by strptime.
       This is the default behavior and can be overridden by calling Time::Piece->use_locale().
       This builds a list of the current locale's day and month names which strptime will use to
       parse with.  Note this is a global override and will affect all Time::Piece instances.

       For instance with a German locale:

           localtime->day_list();

       Returns

           ( 'Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat' )

       While:

           Time::Piece->use_locale();
           localtime->day_list();

       Returns

           ( 'So', 'Mo', 'Di', 'Mi', 'Do', 'Fr', 'Sa' )

   YYYY-MM-DDThh:mm:ss
       The ISO 8601 standard defines the date format to be YYYY-MM-DD, and the time format to be
       hh:mm:ss (24 hour clock), and if combined, they should be concatenated with date first and
       with a capital 'T' in front of the time.

   Week Number
       The week number may be an unknown concept to some readers.  The ISO 8601 standard defines
       that weeks begin on a Monday and week 1 of the year is the week that includes both January
       4th and the first Thursday of the year.  In other words, if the first Monday of January is
       the 2nd, 3rd, or 4th, the preceding days of the January are part of the last week of the
       preceding year.  Week numbers range from 1 to 53.

   Global Overriding
       Finally, it's possible to override localtime and gmtime everywhere, by including the
       ':override' tag in the import list:

           use Time::Piece ':override';

CAVEATS

   Setting $ENV{TZ} in Threads on Win32
       Note that when using perl in the default build configuration on Win32 (specifically, when
       perl is built with PERL_IMPLICIT_SYS), each perl interpreter maintains its own copy of the
       environment and only the main interpreter will update the process environment seen by
       strftime.

       Therefore, if you make changes to $ENV{TZ} from inside a thread other than the main thread
       then those changes will not be seen by strftime if you subsequently call that with the %Z
       formatting code. You must change $ENV{TZ} in the main thread to have the desired effect in
       this case (and you must also call _tzset() in the main thread to register the environment
       change).

       Furthermore, remember that this caveat also applies to fork(), which is emulated by
       threads on Win32.

   Use of epoch seconds
       This module internally uses the epoch seconds system that is provided via the perl
       "time()" function and supported by "gmtime()" and "localtime()".

       If your perl does not support times larger than "2^31" seconds then this module is likely
       to fail at processing dates beyond the year 2038. There are moves afoot to fix that in
       perl. Alternatively use 64 bit perl. Or if none of those are options, use the DateTime
       module which has support for years well into the future and past.

AUTHOR

       Matt Sergeant, matt@sergeant.org Jarkko Hietaniemi, jhi@iki.fi (while creating Time::Piece
       for core perl)

COPYRIGHT AND LICENSE

       Copyright 2001, Larry Wall.

       This module is free software, you may distribute it under the same terms as Perl.

SEE ALSO

       The excellent Calendar FAQ at <http://www.tondering.dk/claus/calendar.html>

BUGS

       The test harness leaves much to be desired. Patches welcome.