Date/EzDate version 1.06 ======================== NAME Date::EzDate - Date and time manipulation made easy SYNOPSIS An EzDate object represents a single point in time and exposes all properties of that point. 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 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. 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 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 *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 *epochday* property which is used for day-granularity calculations. Let's walk through the steps: Load the module and instantiate the object use Date::EzDate; my $mydate = Date::EzDate->new(); # the object defaults to the current date and time output all the basic information # e.g. outputs: 11:11:40 Wed Apr 11, 2001 print $mydate->{'full'}, "\n"; set to tomorrow To move the date forward one day we simply increment the *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"; 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. 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 "YESTERDAY" or "TOMORROW". For example, the following code creates an EzDate object with tomorrow's date: $date = Date::EzDate->new('tomorrow'); STRINGIFICATION EzDate objects stringify to a full representation of the date. So, for example, the following code outputs a string like "Tue Sep 3, 2002 14:01:02": $date = Date::EzDate->new(); print $date, "\n"; The object stringifies to its "default" format, so if you want to change how it stringifies simply change the "default" format. For example, the following code outputs a string like "September 3, 2002": $date->{'default'} = '{month long} {day of month no zero} {year}'; print $date, "\n"; 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. Overloaded Numeric Comparison Operators EzDate overloads the numeric comparison operators. The "epochday" properties of two EzDate objects can be compared using the "==", ">", ">=", "<", "<=" , and "<=>", 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 "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 "epoch second", meaning that two date/times are considered the same only if they are identical down to the second: $date = Date::EzDate->new('January 3, 2001'); *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 is now being used for non-comparison overloads like addition and subtraction. 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 "day of week" properties: $date = Date::EzDate->new('January 3, 2001'); $otherdate = Date::EzDate->new('January 10, 2001'); if ($date->{'day of week'} eq $otherdate->{'day of week'}) { ... } OVERLOADED ADDITION AND SUBTRACTION You can do basic addition and subtraction on EzDate objects to adjust the "epoch day" property (or whatever property is indicated by the "$Date::EzDate::overload" variable). For example, to increment the day of the object, simply increment it with "++" 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++; println $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--; METHODS new([*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'); $mydate->set_format($name, $format) "set_format" allows you to specify a custom format for use later on. For example, suppose you want a format of the form *Monday, June 10, 2002*. You can specify that format using "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 "{" 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 $date->{'{weekday long}, {month long} {day of month}, {year}'}; To delete a custom format, "$mydate-"del_format($name)>. To get the format string itself, use "$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. $mydate->clone() This method returns an EzDate object exactly like the object it was called from. "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. $mydate->set_warnings($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 "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(0); 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::Tie::default_warning = 2; $mydate->next_month([integer]) EzDate lacks an "epochmonth" month property (because months aren't all the same length) so it needed a way to say "same day, next month". Calling "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); "next_month()" handles year boundaries without problem. Calling "next_month()" for a date in December moves the date to January of the next year. $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 "hour am|pm" (e.g. "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 "zero_hour_ampm" with an argument of zero: $date->zero_hour_ampm(0); You can also pass "zero_hour_ampm" as an initial argument for "new": $date = Date::EzDate->new('January 31, 2002 1 am', zero_hour_ampm=>0); after_create "after_create" is intended for use when you are super-classing EzDate. By default, "after_create" does nothing. See "Super-classing Date::EzDate" below for more details. PROPERTIES This section lists the properties of an EzDate object. *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 # makes no sense, but hey, it's your code 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'}; 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. hour Hour in 24 hour clock, 00 to 23. Two digits, with a leading zero where necessary. ampm hour Hour in twelve hour clock, 0 to 12. Two digits, with a leading zero where necessary. ampm *am* or *pm* as appropriate. Returns lowercase. If you set this property the object will adjust to the same day and same hour but in *am* or *pm* as you set. ampm uc, ampm lc "ampm uc" returns *AM* or *PM* uppercased. "ampm lc" returns *am* or *pm* lowercased. min, minute Minute, 00 to 59. Two digits, with a leading zero where necessary. sec, second Second, 00 to 59. Two digits, with a leading zero where necessary. 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 *weekdaynum*: $mydate->{'weekday number'} = 1; Then the object will adjust to Monday Apr 9, 2001. weekday short First three letters of the weekday. *Sun*, *Mon*, *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 *SUNDAY* would a valid assignment. 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 *SUN* would a valid assignment. day of month The day of the month. If you assign to this property the object adjusts to the day in the same month. 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"). 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 *day of month* will be set to 28. 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. month short First three letters of the month. Can be assigned to. Case insensitive in the assignment, so "JANUARY" would be a valid assignment. 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. year Year of the date the object represents. 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. day of year Zero-based Number of days into the year of the date. "yearday" does the same thing. day of year base1 One-based number of days into the year of the date. "yeardaybase1" does the same thing. full A full string representation of the date, e.g. "04:48:01 pm, Tue Apr 10, 2001". You can assign just about any common date and/or time format to this property. *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. *-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 dmy The day, month and year representation of the date, e.g. "03JUN2004". military time, miltime The time formatted as HHMM on a 24 hour clock. For example, 2:20 PM is 1420. clocktime The time formatted as HH::MM AM/PM. minute of day How many minutes since midnight. Useful for doing math with times in a day. Epoch properties The following properties allow you to do date calculations at different granularities. All of these properties are both readable and writable. epoch second The basic Perl epoch integer. epoch hour How many hours since the epoch. epoch minute How many minutes since the epoch. epoch day How many days since the epoch. Read-only properties The following properties are read-only and will crash if you try to assign to them. is leap year True if the year is a leap year. The "is" part is optional. days in month How many days in the month. 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 *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}'}; 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 *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 "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 "{" 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}'; 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. "*" indicates that the code acts differently than standard Unix codes. "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 % 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 *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 "after_create()" method in order to add a custom format. "after_create()" is called by the "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 } 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 "localtime()" and "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. TO DO The following list itemizes features I'd like to add to EzDate. 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 and 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. 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. Next weekday I'd like a function for moving the date forward (or backward) to the next (previous) day of a week. 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. 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. 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 NO WARRANTY of any kind. AUTHOR Miko O'Sullivan miko@idocs.com VERSION Version 0.90 November 1, 2001 Initial release Version 0.91 December 10, 2001 UI enhancements Version 0.92 January 15, 2002 Fixed some bugs Version 0.93 February 11, 2002 Fixed some more bugs 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 "printabledate" and "printabletime" properties, which were just relics from an early project that used EzDate. - Changed "nextmonth" to "next_month" to stay compatible with other methods that were added and will be added. Version 1.01 Aug 14, 2002 - Fixed bug that clones do not return formats - Tightened up the code a little 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 "full" format. - Improved efficiency of custom formats Version 1.04 Sep 03, 2002 - Added ordinals - Added "noon" and "midnight" keywords. 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 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.