Date::Manip::History(3) Twenty years and still going strong


I just realized (Dec 2015) that Date::Manip turned twenty years old earlier this year, so I wanted to write some thoughts I have about Date::Manip.

The history of Date::Manip can be broken into several periods.

Birth of Date::Manip (1995-1996)
1995 was the year I really started using perl to automate some of my common tasks. At the time, I was running programs using a number of different batch systems that needed dates entered in a variety of different formats. It was frustrating to remember what format for what batch system, so I wrote some wrappers which would take a few common formats that I wanted to use and would turn those dates into whatever format the batch system needed.

After a few different wrapper scripts (where I copied the date handling code between the scripts), I gathered all of the date routines into one package.

This was the birth of Date::Manip.

I kept it that way for about half a year. By that time, I was thoroughly in love with perl and wanted to contribute.

At the time, CPAN was just a fledgling site, but in October, I released my first package. It wasn't really a module at that time... it was crudely put together and extremely limited use. Even so, it got some very positive initial feedback which spurred the early growth.

There were several private versions followed by 4 public releases (4.0 through 4.3) during this period.

Soon, I had adopted many of the best practices of the day and converted it to a full-blown module.

Active development (1996-2001)
The next 5 years were extremely active. Based on suggestions and requests, functionality increased dramatically, and before long, Date::Manip was considered the goto module for Date operations.

During this period, a number of other modules came along that did a small subset of the functions of Date::Manip (most of them significantly faster), but none had the scope of Date::Manip.

During this period, I recognized that the single biggest weakness was the inability to correctly handle timezones and daylight saving time. Towards the end of this period (2000 I believe), I began a project to rewrite Date::Manip, but I didn't not have the time needed to really carry it out at that time.

Another weakness was that Date::Manip grew in a random way. As ideas and suggestions came, I added them. There was little planning or forethought involved, and that led to it not having a consistent API.

1998 did see the addition of Recurrences. Although not an extremely widely used piece of functionality, I regard this as the single most important contribution I have ever made. I developed the notation for specifying recurring events, and no other notation has ever come close to matching it's power and flexibility.

This period, starting with the first release in a full module form, included 26 releases (from 5.00 to 5.40).

Minimal maintenance (2001-2008)
During these years, I was able to devote time needed to maintain the existing module, but not to do major development.

As a result, the rewrite project remained incomplete (and in fact, it was barely started).

During this time, due to the fact that no other module could handle timezones correctly, DateTime arrived in 2003. It featured a nice object-oriented interface, and handled timezones.

Over the next few years, it became the de facto standard for date handling in perl.

This period included only 8 releases (5.42 to 5.54).

Rewrite (2009-2010)
In 2009, I decided it was time to fix the timezone problems in Date::Manip . Some people might see this as a waste of time due to the fact that DateTime existed, but I had several thoughts.

First, many people continued to use Date::Manip. This was evident by the number of emails I continued to receive.

Second, there were still things that Date::Manip did better than DateTime including recurrences and parsing.

Third, I love my module, and didn't want to see it die. I'll continue to use it, even if nobody else does.

So, I set out to fix it. It turned out to be a complete rewrite, but in the end, version 6 was released with full timezone handling, even better parsing, and quite a few other features.

Date::Manip was once again very much alive.

This period featured 13 releases (6.00 to 6.14) with an additional 2 maintenance releases of version 5.

Active maintenance (2010-2016)
Although primarily in maintenance mode (due to the fact that Date::Manip does pretty much everything that it was designed to do), active maintenance continues. There is also some development and a large number of significant improvements have been made in this period.

I make regular releases to update the timezone information, fix bugs, and add the occasional new features.

For the foreseeable future, Date::Manip will remain active, and fully capable of handling any common date operation.

Since 6.14, there have been 30 releases to date (6.20 to 6.53) which is averaging about 5 releases per year.


I was curious to see how many other modules are out there that have survived as long as Date::Manip.

The first public release of Date::Manip (though it was not a module yet of course) was version 4.0 on 13-Aug-1995. The first public release to CPAN was version 4.2 released on 23-Oct-1995.

I got a list of all CPAN modules from the wayback machine for 2000 (the earliest version of the list that I could find). Then I checked each of these authors on backpan to see which of these authors had packages (.tar.gz or .tgz files) released prior to 23-Oct-1995.

I found that at the time Date-Manip 4.2 was released there were

   32 authors
   70 packages

So Date::Manip got involved in CPAN very early.

Next, I tried to determine which of those authors and packages are still active. I'm not completely sure about some of the packages because frequently, those old packages have changed maintainers, been renamed, or been incorporated into other packages. So the number of active packages is actually a lower limit.

I found that:

   13 authors are active today
   21 of the packages are active today
   7 of those packages are still maintained by the original author

An active author is one who has released something in the past 3 years. An active module is one that has been updated in the past 3 years.

I apologize if I have missed anyone.

The 7 packages which are older than Date::Manip and are still actively maintained by their original author (though they may have been renamed) are:

   ANDK   Symdump
   GAAS   libwww-perl
   ILYAZ  MathPari
   LDS    GD
   MEWP   sybperl
   PMQS   Filter
   TOMZO  Quota

Congratulations to those authors who have been with perl since the beginning.

Again, if I have missed anyone, please let me know.


This script is free software; you can redistribute it and/or modify it under the same terms as Perl itself.


Sullivan Beck ([email protected])