=head1 NAME

Date::EzDate - Date and time manipulation made easy

=head1 SYNOPSIS

An EzDate object represents a single point in time and exposes all properties
of that point.  It also makes it easy to change those properties to produce
a different point in time.  EzDate has many features, here are a few:

 use Date::EzDate;
 my $mydate = Date::EzDate->new();

 # output some date information
 print $mydate, "\n";  # e.g. output:  Wed Apr 11, 2001 09:06:26

 # go to next day
 $mydate->{'epochday'}++;

 # determine if the date is before some other date
 if ($mydate < 'June 21, 2003')
     {...}

 # output some other date and time information
 # e.g. output:  Thursday April 12, 2001 09:06 am
 print
   $mydate->{'weekday long'},        ' ',
   $mydate->{'month long'},          ' ',
   $mydate->{'day of month'},        ', ',
   $mydate->{'year'},                ' ',
   $mydate->{'ampm hour no zero'},   ':',
   $mydate->{'min'},                 ' ',
   $mydate->{'am pm'},               "\n";

 # go to Monday of same week, but be lazy and don't spell out
 # the whole day or case it correctly
 $mydate->{'weekday long'} = 'MON';

 print $mydate, "\n";  # e.g. output:  Mon Apr 09, 2001 09:06:26

 # go to previous year
 $mydate->{'year'}--;

 print $mydate, "\n";  # e.g. output:  Sun Apr 09, 2000 09:06:26

=head1 INSTALLATION

Date::EzDate can be installed with the usual routine:

 perl Makefile.PL
 make
 make test
 make install

You can also just copy EzDate.pm into the Date/ directory of one of your
library trees.

=head1 DESCRIPTION

Date::EzDate was motivated by the simple fact that I hate dealing with date
and time calculations, so I put all of them into a single easy-to-use object.
The main idea of EzDate is that the object represents a specific date and
time.  A variety of properties tell you information about that date and time
such as hour, minute, day of month, weekday, etc.

The B<real> power of EzDate is that you can assign to (almost) any of those
properties and EzDate will automatically rework the other properties to produce
a new valid date with the property you just assigned.  Properties that can be
kept the same with the new value aren't changed, while those that logically
must change to accomodate the new value are recalculated.  For example,
incrementing I<epochday> by one (i.e. moving the date forward one day) does
not change the hour or minute but does change the day of week.

So, for example, suppose you want to get information about today, then get
information about tomorrow.  That can be done using the I<epochday> property
which is used for day-granularity calculations.  Let's walk through the steps:

=over 4

=item Load the module and instantiate the object

 use Date::EzDate;
 my $mydate = Date::EzDate->new();  # the object defaults to the current date and time

=item output all the basic information

 # e.g. outputs:  11:11:40 Wed Apr 11, 2001
 print $mydate->{'full'}, "\n";

=item set to tomorrow

To move the date forward one day we simply increment the I<epochday> property (number of days
since the epoch).   The time (i.e. hour:min:sec) of the object does not change.

 $mydate->{'epochday'}++;

 # outputs:  11:11:40 Thu Apr 12, 2001
 print $mydate->{'full'}, "\n";

=back

This demonstrates the basic concept: almost any of the properties can be set as well as read and EzDate will take care
of resetting all other properties as needed.

=head1 YESTERDAY and TOMORROW

In addition to initializing the EzDate object with either nothing (i.e. the current day)
or with a string representing a date/time, you can initialize the object with the strings
C<YESTERDAY> or C<TOMORROW>.  For example, the following code creates an EzDate object
with tomorrow's date:

 $date = Date::EzDate->new('tomorrow');

=head1 STRINGIFICATION

EzDate objects stringify to a full representation of the date.  So, for example, the following
code outputs a string like C<Tue Sep 3, 2002 14:01:02>:

 $date = Date::EzDate->new();
 print $date, "\n";

The object stringifies to its C<default> format, so if you want to change how it
stringifies simply change the C<default> format.  For example, the following
code outputs a string like C<September 3, 2002>:

 $date->{'default'} = '{month long} {day of month no zero} {year}';
 print $date, "\n";

=head1 COMPARISON

There are two main ways to compare EzDate objects: by comparing the object directly using the numeric comparison operators,
or by comparing their properties.

=head2 Overloaded Numeric Comparison Operators

EzDate overloads the numeric comparison operators.  The C<epochday> properties of two EzDate objects can be compared
using the C<==>,
C<< E<gt> >>,
C<< E<gt>= >>,
C<< E<lt> >>,
C<< E<lt>= >> , and
C<< E<lt>=E<gt> >>,
operators.  For example, the following code creates
two EzDate objects, then determines if the first object is less than the second:

 $mybday = Date::EzDate->new();
 $yourbday = Date::EzDate->new('tomorrow');

 if ($mybday < $yourbday) {
   ....
 }

Only one of the two items being compared needs be an EzDate object.  The other can be a string representation
of a date.  For example, the following code correctly determines if the given EzDate object is before
June 25, 2003:

 if ($date < 'June 25, 2003') {
    ...
 }

By default, the comparison is done on the C<epochday> property, so two EzDate objects that have the same date
but different times will be considered the same.  If you want to compare based on some other property, set
$Date::EzDate::overload to the name of the property to compare.  For example, the following code sets
the comparison property to C<epoch hour>, meaning that two date/times are considered the same only if
they are identical down to the hour:

 my ($start, $finish);
 $start = Date::EzDate->new('Oct 18, 2006 4pm');
 $finish = Date::EzDate->new('Oct 18, 2006 6pm');

 # outputs false, because both epochdays are the same
 print 'finish is greater than start: ', $finish > $start, "\n";

 # change $Date::EzDate::overload to epochhour
 $Date::EzDate::overload = 'epochhour';

 # output true, because Oct 18, 2006 6pm is
 # greater than Oct 18, 2006 4pm
 print 'finish is greater than start: ', $finish > $start, "\n";

I<PLEASE NOTE>: $Date::EzDate::overload used to be named $Date::EzDate::compare.  I made a non-backwards
compatible change to "overload" because the same variable for indicating default overload is now being
used for non-comparison overloads like addition and subtraction.

=head2 Comparing Properties

The other way to compare dates is to compare their properties.  For example,
you can simple determine if two dates are on the same day of week by using
their C<day of week> properties:

 $date = Date::EzDate->new('January 3, 2001');
 $otherdate = Date::EzDate->new('January 10, 2001');

 if ($date->{'day of week'} eq $otherdate->{'day of week'}) {
    ...
 }

=head1 OVERLOADED ADDITION AND SUBTRACTION

You can do basic addition and subtraction on EzDate objects to adjust the
C<epoch day> property (or whatever property is indicated by the
C<$Date::EzDate::overload> variable). For example, to increment the day of the
object, simply increment it with C<++> like a number.  For example, the
following code moves the day from Jan 31, 2003 to Feb 1, 2003:

 my $date = Date::EzDate->new('Jan 31, 2003');
 print $date, "\n";  # outputs Fri Jan 31, 2003 16:05:27
 $date++;
 print $date;      # outputs Sat Feb 1, 2003 16:05:27

You can also move by more than one day with + or +=.  These two commands do
the same thing:

 $date = $date + 3;
 $date += 3;

Subtraction works the same way.  All of these commands move the object one day
backwards:

 $date = $date - 1;
 $date -= 1;
 $date--;

=head1 METHODS

=head2 new([I<date string>])

Currently, EzDate only accepts a single optional argument when instantiated.
You may pass in either a Perl time integer or a string formatted as DDMMMYYYY.
If you don't pass in any argument then the returned object represents the time
and day at the moment it was created.

The following are valid ways to instantiate an EzDate object:

 # current date and time
 my $date = Date::EzDate->new();

 # a specific date and time
 my $date = Date::EzDate->new('Jan 31, 2001');

 # a date in DDMMMYYYY format
 my $date = Date::EzDate->new('14JAN2003');

 # a little forgiveness is built in (notice oddly place comma)
 my $date = Date::EzDate->new('14 January, 2003');

 # epoch second (23:27:39, Tue Apr 10, 2001 if you're curious)
 my $date = Date::EzDate->new(986959659);

 # yesterday
 my $date = Date::EzDate->new('yesterday');

 # tomorrow
 my $date = Date::EzDate->new('tomorrow');

=head2 $mydate->set_format($name, $format)

C<set_format> allows you to specify a custom format for use later on.
For example, suppose you want a format of the form I<Monday, June 10, 2002>.
You can specify that format using C<set_format> like this:

 $date->set_format('myformat', '{weekday long}, {month long} {day of month}, {year}');
 print $date->{'myformat'}, "\n";

You can also create a custom format by simply assigning the format to its name.
If EzDate sees a C<{> in the value being assigned, it knows that you are
assigning a format, not a date. The set_format line above could be written
like this:

 $date->{'myformat'} = '{weekday long}, {month long} {day of month}, {year}';

Note that it's not necessary to store a custom format if you're only going
to use it once.  If you wanted the format above, but just once, you could
output it like this:

 print $date->{'{weekday long}, {month long} {day of month}, {year}'};

To delete a custom format, C<$mydate->del_format($name)>. To get the format
string itself, use C<$mydate->get_format($name)>.

If you use the same custom format in a lot of different places in your
project, you might find it easier to create your own customer super-class of
Date::EzDate so that you can set the custom formats in one place.  See
"Super-classing Date::EzDate" below.

=head2 $mydate->clone()

This method returns an EzDate object exactly like the object it was called
from.  C<clone> is much cheaper than creating a new EzDate object and then
setting the new object to have the same properties as another EzDate object.

=head2 $mydate->set_warnings($warning_level)

When EzDate receives invalid instructions, by default it outputs a warning
and continues.  For example, if you use a time/date format that EzDate doesn't
recognize, it outputs a warning to STDERR and ens the attempt to set the
date/time.  There are two other ways that EzDate could handle the error: it
could ignore the error completely, or it could end the entire program.

You can set which error handling you prefer with the C<set_warnings> method.
The first and only argument indicates how to handle errors.  There are three
possible values:

 0	Do not handle error in any way
 1	Output error to STDERR (default)
 2	Output to STDERR and exit program

So, for example, the following code sets the warnings to level 2:

 $date->set_warnings(2);

You can set the global default warning level by setting
$Date::EzDate::default_warning.  For example, the following code sets the
global default level to 2:

 $Date::EzDate::default_warning = 2;

=head2 $mydate->next_month([integer])

EzDate lacks an C<epochmonth> month property (because months aren't all the
same length) so it needed a way to say "same day, next month".  Calling
C<next_month> w/o any argument moves the object to the same day in the next
month. If the day doesn't exist in the next month, such as if you move from
Jan 31 to Feb, then the date is moved back to the last day of the next month.

The only argument, which defaults to 1, allows you to move backward or forward
any number of months. For example, the following command moves the date forward
two months:

 $mydate->next_month(2);

This command moves the date backward three months:

 $mydate->next_month(-3);

C<next_month()> handles year boundaries without problem.  Calling
C<next_month()> for a date in December moves the date to January of the next
year.

=head2 $mydate->zero_hour_ampm(1|0)

In general, EzDate operates on the principal that only date/time properties
that are explicitly changed are changed.  However, this rule was confusing
people in one manner, so I changed the default behavior.  If you set the hour
using the format C<hour am|pm> (e.g. C<4 am> without specifying the minute or
second, then EzDate assumes you meant to set the minute and second to 0.  So,
the following string sets the object to exactly 4:00:00 pm:

 $date = Date::EzDate->new('4 pm');

If you would prefer the old behavior where the time would be set to whatever
the current minute and second are, then call C<zero_hour_ampm> with an argument
of zero:

 $date->zero_hour_ampm(0);

You can also pass C<zero_hour_ampm> as an initial argument for C<new>:

 $date = Date::EzDate->new('January 31, 2002 1 am', zero_hour_ampm=>0);

=head2 after_create

C<after_create> is intended for use when you are super-classing EzDate.  By
default, C<after_create> does nothing.  See "Super-classing Date::EzDate"
below for more details.

=head2 $start_date->date_range_string($end_date)

C<date_range_string> outputs a string representing the range of days
from the EzDate date to some other date.  The routine tries to make
the string as concise as possible, so that months and years are not
repeated if they are the same in both days.  The single argument
to C<date_range_string> is another EzDate object.

 # same month and year
 # outputs Mar 5-7, 2004
 $start = Date::EzDate->new('Mar 5, 2004');
 $end = Date::EzDate->new('Mar 7, 2004');
 print $start->date_range_string($end);

 # same year, different months
 # outputs Feb 20-Mar 3, 2004
 $start = Date::EzDate->new('feb 20, 2004');
 $end = Date::EzDate->new('mar 3, 2004');
 print $start->date_range_string($end);

 # different years
 # outputs Dec 23, 2004-Jan 3, 2005
 $start = Date::EzDate->new('Dec 23, 2004');
 $end = Date::EzDate->new('Jan 3, 2005');
 print $start->date_range_string($end);

It does not matter if the EzDate object is earlier or later than the
second date.  The function will always return them with the earlier
date first.

You can pass either an EzDate object or a string.  So, for example, the
following blocks of code output the same thing:

 # outputs Mar 5-7, 2004
 $start = Date::EzDate->new('Mar 5, 2004');
 $end = Date::EzDate->new('Mar 7, 2004');
 print $start->date_range_string($end);

 # outputs Mar 5-7, 2004
 $start = Date::EzDate->new('Mar 5, 2004');
 print $start->date_range_string('Mar 7, 2004');

If both dates are the same day, then just that date will be returned:

 # same day
 # outputs Dec 23, 2004
 $start = Date::EzDate->new('Dec 23, 2004');
 print $start->date_range_string('Dec 23, 2004');

C<date_range_string> can also be called a static method, i.e., without
ever explicitly defining an EzDate object:

 # outputs Mar 5-7, 2004
 print Date::EzDate::date_range_string('Mar 5, 2004', 'Mar 7, 2004');

If you load EzDate using the ':all' param, the function call is even simpler:

 # note use of ':all'
 use Date::EzDate ':all';

 # outputs Mar 5-7, 2004
 print date_range_string('Mar 5, 2004', 'Mar 7, 2004');

Array references in the argument list are expanded. So, for example,
the following two lines of code produce the same thing:

 print date_range_string('May 3, 2005', 'May 5, 2005');
 print date_range_string( ['May 3, 2005', 'May 5, 2005'] );

This behavior was added to accomodate the output from C<day_lumps>.
See the documentation of C<day_lumps> for a practical example of
this feature.

=head2 $start_time->time_range_string($end_time)

C<time_range_string> returns a string representation of a range of minutes.
For example, the following code outputs the range from 10:00 am to 2:00 pm:

 # outputs 10:00am-2:00pm
 $start = Date::EzDate->new('10:00am');
 $end = Date::EzDate->new('2:00pm');
 print $start->time_range_string($end);

C<time_range_string> always tries to return the string as concisely as possible,
so if the two times have the same am/pm designation then am/pm is only output once:

 # outputs 10:00-11:00am
 $start = Date::EzDate->new('10:00am');
 $end = Date::EzDate->new('11:00am');
 print $start->time_range_string($end);

C<time_range_string> can also be called as a static method, i.e. without
actually creating any EzDate objects:

 # outputs 8:00-9:00pm
 print Date::EzDate::time_range_string('8pm', '9pm');

If you load EzDate using the ':all' param, the function call is even simpler:

 # note use of ':all'
 use Date::EzDate ':all';

 # outputs 8:00-9:00pm
 print time_range_string('8pm', '9pm');

The earlier time is always output first.  If you only pass times, not dates,
then EzDate assumes that both times are on the same day and outputs the
earlier time first:

 # outputs 8:00-9:00pm
 print time_range_string('8pm', '9pm');

If the time range crosses over midnight, you should explicitly indicate
both dates:

 # output jan 21, 2005 8pm
 print time_range_string('jan 21, 2005 9pm', 'jan 22, 2005 5am');

=head2 day_lumps(@dates)

C<day_lumps> groups an array of dates into "lumps" of contiguous dates.
For example, consider the following dates:

 Jan 3, 2005
 Jan 4, 2005
 Jan 5, 2005
 Jan 6, 2005
 Jan 10, 2005
 Jan 15, 2005
 Jan 16, 2005
 Jan 17, 2005

That list of dates could be more concisely expressed like this:

 Jan 3-6, 2005
 Jan 10, 2005
 Jan 15-17, 2005

C<day_lumps> produces an array of day spans, each span containing
the start and end date of a single "lump".  Here's the code to
produce the output from the example above:

# note use of ':all'
 use Date::EzDate ':all';

 my (@dates, @lumps);

 @dates = (
   'Jan 3, 2005',
   'Jan 4, 2005',
   'Jan 5, 2005',
   'Jan 6, 2005',
   'Jan 10, 2005',
   'Jan 15, 2005',
   'Jan 16, 2005',
   'Jan 17, 2005',
 );

 @lumps = day_lumps(@dates);

 foreach my $lump (@lumps)
    { print date_range_string($lump), "\n" }

=head1 PROPERTIES

This section lists the properties of an EzDate object.

I<Properties are case and space insensitive>.  Properties can be in upper or
lower case, and you can put spaces anywhere to make them more readable.  For
example, the following properties are all the same:

 weekdaylong
 WEEKDAYLONG
 WeekDay Long
 Wee Kdaylong  # ugly but works

Also, certain words can always be abbreviated.

 minute  ==  min
 second  ==  sec
 number  ==  num
 ordinal ==  num

So, for example, the following two properties are the same:

 $mydate->{'minute of day'};
 $mydate->{'min of day'};

=head2 Basic properties

All of these properties are both readable and writable.  Where there might be
some confusion about what happens if you assign to the property more detail
is given.

=over 4

=item hour

Hour in 24 hour clock, 00 to 23.  Two digits, with a leading zero where necessary.

=item ampm hour

Hour in twelve hour clock, 0 to 12.  Two digits, with a leading zero where necessary.

=item ampm

I<am> or I<pm> as appropriate.  Returns lowercase.  If you set this property the object will adjust to the
same day and same hour but in I<am> or I<pm> as you set.

=item ampm uc, ampm lc

C<ampm uc> returns I<AM> or I<PM> uppercased.  C<ampm lc> returns I<am> or I<pm> lowercased.

=item min, minute

Minute, 00 to 59.  Two digits, with a leading zero where necessary.

=item sec, second

Second, 00 to 59.  Two digits, with a leading zero where necessary.

=item weekday number

Number of the weekday.  This number is zero-based, so Sunday is 0, Monday is 1, etc.
If you assign to this property the object will reset the date to the assigned
weekday of the same week.  So, for example, if the object represents
Saturday Apr 14, 2001, and you assign 1 (Monday) to I<weekdaynum>:

 $mydate->{'weekday number'} = 1;

Then the object will adjust to Monday Apr 9, 2001.

=item weekday short

First three letters of the weekday.  I<Sun>, I<Mon>, I<Tue>, etc.  If you
assign to this property the object will adjust to that day in the same week.
When you assign to this property EzDate actually only pays attention to the
first three letters and ignores case, so I<SUNDAY> would a valid assignment.

=item weekday long

Full name of the weekday.  If you assign to this property the object will
adjust to the day in the same week.  When you assign to this property EzDate
actually only pays attention to the first three letters and ignores case, so
I<SUN> would a valid assignment.

=item day of month

The day of the month.  If you assign to this property the object adjusts to the
day in the same month.

=item day of month ordinal word, day of month ordinal number

The day of month expressed as either an ordinal word (e.g. "Third") or as an
ordinal number (e.g. "3rd").

=item month number

Zero-based number of the month.  January is 0, February is 1, etc. If you
assign to this property the object will adjust to the same month-day in the
assigned month.  If the current day is greater than allowed in the assigned
month then the day will adjust to the maximum day of the assigned month.  So,
for example, if the object is set to 31 Dec 2001 and you assign the month to
February (1):

 $mydate->{'month number'} = 1;

Then I<day of month> will be set to 28.

=item month number base 1

1 based number of the month for those of us who are used to thinking of January as 1,
February as 2, etc.  Can be assigned to.

=item month short

First three letters of the month.  Can be assigned to.  This property is case
insensitive, so "jAN" is as valid as "Jan".  The assignment only looks at the
first three letters of the input string, so "JANUARY" would be a valid
assignment.

=item month long

Full name of the month.  Can be assigned to.  In the assignment, EzDate only
pays attention to the first three letters and ignores case.

=item year

Year of the date the object represents.

=item year two digits

The last two digits of the year.  If you assign to this property, EzDate assumes you mean to
use the same first two digits.  Therefore, if the current date of the object is 1994 and you assign
'12' then the year will be 1912... quite possibly not what you intended.

=item day of year

Zero-based Number of days into the year of the date.  C<yearday> does the same thing.

=item day of year base1

One-based number of days into the year of the date.  C<yeardaybase1> does the same thing.

=item full

A full string representation of the date, e.g. C<04:48:01 pm, Tue Apr 10, 2001>.
You can assign just about any common date and/or time format to this property.

I<Please take the previous statement as a challenge.>  I've aggressively tried
to find formats that EzDate can't understand.  When I've found one, I've
modified the code to accomodate it.  If you have some reasonably unambiguous
date format that EzDate is unable to parse correctly, please send it to me.
I<-Miko>

When assigning a full date/time string, you can use 'noon' and 'midnight' to
indicate specific times.  So, for example, this string indicates July 25, 2003
and noon:

 $mydate = Date::EzDate->new('July 23 2003 noon');
 print $mydate->{'full'}; # outputs Wed Jul 23, 2003 12:00:00

=item dayandtime

Outputs the date and the time (to minute granularity).

 $mydate = Date::EzDate->new('December 23 2003 17:45');
 print $mydate->{'dayandtime'}; # outputs Dec 23 2003, 5:45pm

C<dayandtime> is the default output format.

=item dmy

The day, month and year representation of the date, e.g. C<03JUN2004>.

=item dayparam

Returns the day of the month, the short month name (lowercased), and the full
year.  C<dayparam> is a convenient string for passing as a parameter to scripts.
It consists of just alphanumerics (so it need not be escaped in any way), it
is easily human readable, and is completely unambiguous.

Actually, dayparam looks about the same as dmy, but it lowercased.

 $date = Date::EzDate->new('Dec 1, 2004 12:54:15');
 print $date->{'dayparam'}; # outputs 01dec2004

=item military time, miltime

The time formatted as HHMM on a 24 hour clock.  For example, 2:20 PM is 1420.

=item clocktime

The time formatted as HH::MM AM/PM.

=item minute of day

How many minutes since midnight.  Useful for doing math with times in a day.

=item iso8601

Returns the date in the format YYYY-MM-DD HH:MM:SS.

=back

=head2 Epoch properties

The following properties allow you to do date calculations at different granularities. All of these properties are
both readable and writable.

=over 4

=item epoch second

The basic Perl epoch integer.

=item epoch hour

How many hours since the epoch.

=item epoch minute

How many minutes since the epoch.

=item epoch day

How many days since the epoch.

=back

=head2 Read-only properties

The following properties are read-only and will crash if you try to assign to them.

=over 4

=item is leap year

True if the year is a leap year. The "is" part is optional.

=item days in month

How many days in the month.

=back

=head1 CUSTOM FORMATS

You'll probably often want to retrieve more than one piece of information
about a date/time at once.  You could, of course, do this by getting each
property individually and concatenating them together.  For example, you might
want to get the date in the format I<Monday, June 10, 2002>.  You could build
that string like this:

 $str =
   $date->{'weekday long'} . ', ' .
   $date->{'month long'} . ' ' .
   $date->{'day of month'} . ', ' .
   $date->{'year'};

That's a lot of typing, however, and it's difficult to tell from the code what
the final string will look like.  To make life EZ, EzDate allows you embed
several date properties in a single call.  Just surround each property with
braces:

 $str = $date->{'{weekday long}, {month long} {day of month}, {year}'};

=head2 Storing custom formats

EzDate allows you to store your custom date formats for repeated calls.  This comes in handy for
formats that are needed in several places throughout a project.  For example, suppose you want all
your dates in the format I<Monday, June 10, 2002>. Of course, you could output them using a
format string like in the example above, but even that will get tiring if you need to output the
same format in several places.  Much easier would be to set the format once.  To do so, just call the
C<set_format> method with the name of the format and the format itself:

 $date->set_format('myformat', '{weekday long}, {month long} {day of month}, {year}');
 print $date->{'myformat'}, "\n";

You can also create a custom format by simply assigning the format to its name.
If EzDate sees a C<{> in the value being assigned, it knows that you are
assigning a format, not a date. The set_format line above could be written like this:

 $date->{'myformat'} = '{weekday long}, {month long} {day of month}, {year}';

=head2 Un*x-style date formatting

To make the Unix types happy you can format your dates using standard Un*x date codes.  The format string
must contain at least one % or EzDate won't know it's a format string. For example, you could output a
date like this:

 print $mydate->{'%h %d, %Y %k:%M %p'}, "\n";

which would give you something like this:

 Oct 31, 2001 02:43 pm

Following is a list of codes.  C<*> indicates that the code acts differently than
standard Unix codes.  C<x> indicates that the code does not exists in standard Unix
codes.

 %a   weekday, short                               Mon
 %A   weekday, long                                Monday
 %b * hour, 12 hour format, no leading zero        2
 %B * hour, 24 hour format, no leading zero        2
 %c   full date                                    Mon Aug 10 14:40:38
 %d   numeric day of the month                     10
 %D   date as month/date/year                      08/10/98
 %e x numeric month, 1 to 12, no leading zero      8
 %f x numeric day of month, no leading zero        3
 %h   short month                                  Aug
 %H   hour 00 to 23                                14
 %j   day of the year, 001 to 366                  222
 %k   hour, 12 hour format                         14
 %m   numeric month, 01 to 12                      08
 %M   minutes                                      40
 %n   newline
 %P x AM/PM                                        PM
 %p * am/pm                                        pm
 %r   hour:minute:second AM/PM                     02:40:38 PM
 %s   number of seconds since start of 1970        902774438
 %S   seconds                                      38
 %t   tab
 %T   hour:minute:second (24 hour format)          14:40:38
 %w   numeric day of the week, 0 to 6, Sun is 0    1
 %y   last two digits of the year                  98
 %Y   four digit year                              1998
 %%   percent sign                                 %

=head1 EXTENDING

If you plan on using the same custom formats in several different places in
your project, you might find it easier to super-class EzDate so that your
formats are loaded automatically whenever an object is created.

To super-class EzDate, it is actually necessary to super-class I<two> classes:
Date::EzDate and Date::EzDate::Tie.  For example, suppose you want to create
a class called MyDateClass.  To do that, create a file called MyDateClass.pm,
store it in the root of one of the directories in your @INC path.  Then put
both MyDateClass and MyDateClass::Tie packages in that file.  The following
code can be used as a working template for super-classing EzDate.  Notice that
we override the C<after_create()> method in order to add a custom format.
C<after_create()> is called by the  C<new> method after the new object has
been created but before it is returned.

 package MyDateClass;
 use strict;
 use Date::EzDate;
 use vars qw(@ISA);
 @ISA = ('Date::EzDate');

 # override after_create
 sub after_create {
   my ($self) = @_;
   $self->set_format('myformat', '{weekdaylong}, {monthlong} {dayofmonth}, {year}');
 }

 ##############################################################
 package MyDateClass::Tie;
 use strict;
 use vars qw(@ISA);
 @ISA = ('Date::EzDate::Tie');

 # return true
 1;

You can then load your class with code like this:

 use MyDateClass;
 my ($date, $str);

 $date = MyDateClass->new();
 print $date->{'myformat'}, "\n";

EzDate is really two packages in one: the public object, and the private tied hash (which
is where all the date info is stored).   If you want to add a public method, add it in the
main class (e.g. MyDateClass, not MyDateClass::Tie).  Usually in those situations you'll
need to use the private tied hash object (i.e. the object used internally by the tying
mechanism).  To get to that tied object, used the tied method, like this:

 sub my_method {
    my ($self) = @_;
    my $ob = tied(%{$self});

    # do stuff with $self and $ob
 }

=head1 LIMITATIONS, KNOWN/SUSPECTED BUGS

The routine for setting the year has an off-by-one problem which is kludgly
fixed but which I haven't been able to properly solve.

EzDate is entirely based on the C<localtime()> and C<timelocal()> functions, so
it inherits their limitations. On my computer that means it can't handle dates
before Jan 1, 1902 or after Dec 31, 2037.  Your mileage may vary.

=head1 TO DO

The following list itemizes features I'd like to add to EzDate.

=over 4

=item Time zone properties

The current version does not address time zone issues.  Frankly, I haven't
been able to figure out how best to deal with them.  I'd like a system where
the object knows what time zone it's in and if it's daylight savings time.
Changing to another time zone changes the other properties such that the
object is in the same moment in time in the new time zone as it was in the old
time zone.  For example, if the object represents 5pm in the Eastern Time Zone
(e.g. where New York City is) and its time zone is changed to Pacific Time
(e.g. where Los Angeles is) then the object would have a time of 2pm.

=item Assignment based on format

Right now the formatted string feature is read-only.  It might be useful if
the date could be assigned based on a format.  So, for example, you could set
the date as Nov 1, 2001 like this:

 $mydate->{'%h %d %Y'} = 'Nov 1 2001';

This would come in handy when dealing with weirdly formatted dates.  However,
EzDate is already quite robust about handling weirdly formatted dates, so this
feature is not as pressingly needed as it might seem.

=item Next weekday

I'd like a function for moving the date forward (or backward) to the next
(previous) day of a week.

=item Time interval object

An EzDate object represents a point in time.  I'd also like to have an object
that represents an interval of time.  For example, an interval object could
represent "2 days, 3 hours, 18 seconds". An object like that could then be used
for calculating the difference between two dates.

I'm currently working on this feature.

=item Greater range of available dates

Currently EzDate inherits the limitations of localtime, which generally means
it can't handle dates before about 1902 or after about 2037.  I'd like to
stretch EzDate so it can handle a greater range of dates.  Ideally, it should
handle dates from the Big Bang to the Big Crunch, but let's start with recorded
human history.

=back

=head1 TERMS AND CONDITIONS

Copyright (c) 2001-2003 by Miko O'Sullivan.  All rights reserved.  This program is
free software; you can redistribute it and/or modify it under the same terms
as Perl itself. This software comes with B<NO WARRANTY> of any kind.

=head1 AUTHORS

Miko O'Sullivan
F<miko@idocs.com>

DST patch submitted by Greg Estep.

=head1 VERSION

=over 4

=item Version 0.90    November 1, 2001

Initial release

=item Version 0.91    December 10, 2001

UI enhancements

=item Version 0.92    January  15, 2002

Fixed some bugs

=item Version 0.93    February 11, 2002

Fixed some more bugs

=item Version 1.00    July 5, 2002

Fixed a bug in next_month.

Added a lotta functionality:

- Space insensitive property names

- Custom formats using braced property names

- Stored custom formats

- More supportive of super-classing

- All that and yet actually decreased the volume of code

- Decided this sucker's ready for 1.00 release

Also made a few minor not-so-backward-compatible changes:

- Got rid of the C<printabledate> and C<printabletime> properties, which
  were just relics from an early project that used EzDate.

- Changed C<nextmonth> to C<next_month> to stay compatible with other
  methods that were added and will be added.

=item Version 1.01    Aug 14, 2002

- Fixed bug that clones do not return formats

- Tightened up the code a little

=item Version 1.02    Sep 03, 2002

- Added ability to set a format by just assigning it to a key

- Added warnings to situations where the IM in DWIM isn't always clear.

- Added stringification of EzDate object

- Added overloaded comparison operators

- Made not-backward-compatible change to the C<full> format.

- Improved efficiency of custom formats

=item Version 1.04    Sep 03, 2002

- Added ordinals

- Added "noon" and "midnight" keywords.

=item Version 1.05    Dec 11, 2002

- Added format yyyy-mm-dd

- Added feature that if Date::EzDate->new() is called with an unrecognized
 format, then undef is returned.  This allows you to check formats for validity.

- Fixed off-by-one problem that occurred when, for example, moving Jan 1, 2003 back one year to 2002

=item Version 1.06    Mar 11, 2003

- Non-backwards compatible change: changed $compare global to $overload.

- Non-backwards compatible change: EzDate objects now stringify to the "default" format instead of the "full" format.

- Added overloading of addition and subtraction.

- Added recognition of the following time format, which is used by PostGreSql: 2003-02-13 12:35:49.480975-05

- Fixed bug in which days of DST changeover produced off-by-one problem when setting hours.

- Fixed bug in which the epochday value for dates before the epoch are off-by-one.

=item Version 1.07    May 21, 2003

- Implemented fix for DST problem.  Used patch submitted by Greg Estep. Thanks Greg!

=item Version 1.08    June 10, 2003

- Changed test.pl: removed test that incorrectly relied on the host
  having a specific epoch.  No change to the module itself.

=item Version 1.09

- Fixed daylight savings time, again.  This time I think the fix will actually fix it. Sheesh.

- Added dayparam as built-in format.

- Fixed bug: system did not recognize "day of week short" in all the places it should.

- Added some default formats: fullday, fulldate, dayandtime

- changed default format to dayandtime

- Fixed some bogus documentation.

- Fixed bug such that new method dies on invalid date format even when
  it is supposed to just give a warning.

- Added date_range_string, time_range_string,  methods

- Removing MANY tests from test.pl.  I discovered that the tests that
were failing were not proper tests for the module.

- Fixed monthnum issue.  Now you can set monthnum to any integer, and it will
roll the month forward or backwards that many times.  The resulting monthnum
will still always be from 0..11.

- Clarified example of using $Date::EzDate::overload

=item Version 1.10

- Removed Debug::ShowStuff call from module.  That shouldn't have been in the
distribution.

=item Version 1.11

This version had been considered the final release of Date::EzDate.  However,
as of verson 1.12 it is active again.

=item Version 1.12 June 12, 2012

In version 1.11 I had stated that Date::EzDate would no longer be developed further
or supported.  Basically, I changed my mind and am now developing it again.

- Added date format "Tue Jun 12 13:03:28 2012".

=item Version 1.13

- Minor tidying up of documentation.

=item Version 1.14

- Minor tidying up of documentation.

- Fixing some prerequisite issues.

=back

